YQ Connector: support managed ClickHouse

Со стороны dqrun можно обратиться к инстансу коннектора, который работает на streaming стенде, и извлечь данные из облачного CH.

1 files changed, 4766 insertions, 0 deletions

diff --git a/contrib/libs/clang14/lib/Sema/SemaExprObjC.cpp b/contrib/libs/clang14/lib/Sema/SemaExprObjC.cpp
new file mode 100644
index 0000000000..4702c405fb
--- /dev/null
+++ b/contrib/libs/clang14/lib/Sema/SemaExprObjC.cpp
@@ -0,0 +1,4766 @@
+//===--- SemaExprObjC.cpp - Semantic Analysis for ObjC Expressions --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements semantic analysis for Objective-C expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/AST/TypeLoc.h"
+#include "clang/Analysis/DomainSpecific/CocoaConventions.h"
+#include "clang/Basic/Builtins.h"
+#include "clang/Edit/Commit.h"
+#include "clang/Edit/Rewriters.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/Initialization.h"
+#include "clang/Sema/Lookup.h"
+#include "clang/Sema/Scope.h"
+#include "clang/Sema/ScopeInfo.h"
+#include "clang/Sema/SemaInternal.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/ConvertUTF.h"
+
+using namespace clang;
+using namespace sema;
+using llvm::makeArrayRef;
+
+ExprResult Sema::ParseObjCStringLiteral(SourceLocation *AtLocs,
+                                        ArrayRef<Expr *> Strings) {
+  // Most ObjC strings are formed out of a single piece.  However, we *can*
+  // have strings formed out of multiple @ strings with multiple pptokens in
+  // each one, e.g. @"foo" "bar" @"baz" "qux"   which need to be turned into one
+  // StringLiteral for ObjCStringLiteral to hold onto.
+  StringLiteral *S = cast<StringLiteral>(Strings[0]);
+
+  // If we have a multi-part string, merge it all together.
+  if (Strings.size() != 1) {
+    // Concatenate objc strings.
+    SmallString<128> StrBuf;
+    SmallVector<SourceLocation, 8> StrLocs;
+
+    for (Expr *E : Strings) {
+      S = cast<StringLiteral>(E);
+
+      // ObjC strings can't be wide or UTF.
+      if (!S->isAscii()) {
+        Diag(S->getBeginLoc(), diag::err_cfstring_literal_not_string_constant)
+            << S->getSourceRange();
+        return true;
+      }
+
+      // Append the string.
+      StrBuf += S->getString();
+
+      // Get the locations of the string tokens.
+      StrLocs.append(S->tokloc_begin(), S->tokloc_end());
+    }
+
+    // Create the aggregate string with the appropriate content and location
+    // information.
+    const ConstantArrayType *CAT = Context.getAsConstantArrayType(S->getType());
+    assert(CAT && "String literal not of constant array type!");
+    QualType StrTy = Context.getConstantArrayType(
+        CAT->getElementType(), llvm::APInt(32, StrBuf.size() + 1), nullptr,
+        CAT->getSizeModifier(), CAT->getIndexTypeCVRQualifiers());
+    S = StringLiteral::Create(Context, StrBuf, StringLiteral::Ascii,
+                              /*Pascal=*/false, StrTy, &StrLocs[0],
+                              StrLocs.size());
+  }
+
+  return BuildObjCStringLiteral(AtLocs[0], S);
+}
+
+ExprResult Sema::BuildObjCStringLiteral(SourceLocation AtLoc, StringLiteral *S){
+  // Verify that this composite string is acceptable for ObjC strings.
+  if (CheckObjCString(S))
+    return true;
+
+  // Initialize the constant string interface lazily. This assumes
+  // the NSString interface is seen in this translation unit. Note: We
+  // don't use NSConstantString, since the runtime team considers this
+  // interface private (even though it appears in the header files).
+  QualType Ty = Context.getObjCConstantStringInterface();
+  if (!Ty.isNull()) {
+    Ty = Context.getObjCObjectPointerType(Ty);
+  } else if (getLangOpts().NoConstantCFStrings) {
+    IdentifierInfo *NSIdent=nullptr;
+    std::string StringClass(getLangOpts().ObjCConstantStringClass);
+
+    if (StringClass.empty())
+      NSIdent = &Context.Idents.get("NSConstantString");
+    else
+      NSIdent = &Context.Idents.get(StringClass);
+
+    NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
+                                     LookupOrdinaryName);
+    if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
+      Context.setObjCConstantStringInterface(StrIF);
+      Ty = Context.getObjCConstantStringInterface();
+      Ty = Context.getObjCObjectPointerType(Ty);
+    } else {
+      // If there is no NSConstantString interface defined then treat this
+      // as error and recover from it.
+      Diag(S->getBeginLoc(), diag::err_no_nsconstant_string_class)
+          << NSIdent << S->getSourceRange();
+      Ty = Context.getObjCIdType();
+    }
+  } else {
+    IdentifierInfo *NSIdent = NSAPIObj->getNSClassId(NSAPI::ClassId_NSString);
+    NamedDecl *IF = LookupSingleName(TUScope, NSIdent, AtLoc,
+                                     LookupOrdinaryName);
+    if (ObjCInterfaceDecl *StrIF = dyn_cast_or_null<ObjCInterfaceDecl>(IF)) {
+      Context.setObjCConstantStringInterface(StrIF);
+      Ty = Context.getObjCConstantStringInterface();
+      Ty = Context.getObjCObjectPointerType(Ty);
+    } else {
+      // If there is no NSString interface defined, implicitly declare
+      // a @class NSString; and use that instead. This is to make sure
+      // type of an NSString literal is represented correctly, instead of
+      // being an 'id' type.
+      Ty = Context.getObjCNSStringType();
+      if (Ty.isNull()) {
+        ObjCInterfaceDecl *NSStringIDecl =
+          ObjCInterfaceDecl::Create (Context,
+                                     Context.getTranslationUnitDecl(),
+                                     SourceLocation(), NSIdent,
+                                     nullptr, nullptr, SourceLocation());
+        Ty = Context.getObjCInterfaceType(NSStringIDecl);
+        Context.setObjCNSStringType(Ty);
+      }
+      Ty = Context.getObjCObjectPointerType(Ty);
+    }
+  }
+
+  return new (Context) ObjCStringLiteral(S, Ty, AtLoc);
+}
+
+/// Emits an error if the given method does not exist, or if the return
+/// type is not an Objective-C object.
+static bool validateBoxingMethod(Sema &S, SourceLocation Loc,
+                                 const ObjCInterfaceDecl *Class,
+                                 Selector Sel, const ObjCMethodDecl *Method) {
+  if (!Method) {
+    // FIXME: Is there a better way to avoid quotes than using getName()?
+    S.Diag(Loc, diag::err_undeclared_boxing_method) << Sel << Class->getName();
+    return false;
+  }
+
+  // Make sure the return type is reasonable.
+  QualType ReturnType = Method->getReturnType();
+  if (!ReturnType->isObjCObjectPointerType()) {
+    S.Diag(Loc, diag::err_objc_literal_method_sig)
+      << Sel;
+    S.Diag(Method->getLocation(), diag::note_objc_literal_method_return)
+      << ReturnType;
+    return false;
+  }
+
+  return true;
+}
+
+/// Maps ObjCLiteralKind to NSClassIdKindKind
+static NSAPI::NSClassIdKindKind ClassKindFromLiteralKind(
+                                            Sema::ObjCLiteralKind LiteralKind) {
+  switch (LiteralKind) {
+    case Sema::LK_Array:
+      return NSAPI::ClassId_NSArray;
+    case Sema::LK_Dictionary:
+      return NSAPI::ClassId_NSDictionary;
+    case Sema::LK_Numeric:
+      return NSAPI::ClassId_NSNumber;
+    case Sema::LK_String:
+      return NSAPI::ClassId_NSString;
+    case Sema::LK_Boxed:
+      return NSAPI::ClassId_NSValue;
+
+    // there is no corresponding matching
+    // between LK_None/LK_Block and NSClassIdKindKind
+    case Sema::LK_Block:
+    case Sema::LK_None:
+      break;
+  }
+  llvm_unreachable("LiteralKind can't be converted into a ClassKind");
+}
+
+/// Validates ObjCInterfaceDecl availability.
+/// ObjCInterfaceDecl, used to create ObjC literals, should be defined
+/// if clang not in a debugger mode.
+static bool ValidateObjCLiteralInterfaceDecl(Sema &S, ObjCInterfaceDecl *Decl,
+                                            SourceLocation Loc,
+                                            Sema::ObjCLiteralKind LiteralKind) {
+  if (!Decl) {
+    NSAPI::NSClassIdKindKind Kind = ClassKindFromLiteralKind(LiteralKind);
+    IdentifierInfo *II = S.NSAPIObj->getNSClassId(Kind);
+    S.Diag(Loc, diag::err_undeclared_objc_literal_class)
+      << II->getName() << LiteralKind;
+    return false;
+  } else if (!Decl->hasDefinition() && !S.getLangOpts().DebuggerObjCLiteral) {
+    S.Diag(Loc, diag::err_undeclared_objc_literal_class)
+      << Decl->getName() << LiteralKind;
+    S.Diag(Decl->getLocation(), diag::note_forward_class);
+    return false;
+  }
+
+  return true;
+}
+
+/// Looks up ObjCInterfaceDecl of a given NSClassIdKindKind.
+/// Used to create ObjC literals, such as NSDictionary (@{}),
+/// NSArray (@[]) and Boxed Expressions (@())
+static ObjCInterfaceDecl *LookupObjCInterfaceDeclForLiteral(Sema &S,
+                                            SourceLocation Loc,
+                                            Sema::ObjCLiteralKind LiteralKind) {
+  NSAPI::NSClassIdKindKind ClassKind = ClassKindFromLiteralKind(LiteralKind);
+  IdentifierInfo *II = S.NSAPIObj->getNSClassId(ClassKind);
+  NamedDecl *IF = S.LookupSingleName(S.TUScope, II, Loc,
+                                     Sema::LookupOrdinaryName);
+  ObjCInterfaceDecl *ID = dyn_cast_or_null<ObjCInterfaceDecl>(IF);
+  if (!ID && S.getLangOpts().DebuggerObjCLiteral) {
+    ASTContext &Context = S.Context;
+    TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
+    ID = ObjCInterfaceDecl::Create (Context, TU, SourceLocation(), II,
+                                    nullptr, nullptr, SourceLocation());
+  }
+
+  if (!ValidateObjCLiteralInterfaceDecl(S, ID, Loc, LiteralKind)) {
+    ID = nullptr;
+  }
+
+  return ID;
+}
+
+/// Retrieve the NSNumber factory method that should be used to create
+/// an Objective-C literal for the given type.
+static ObjCMethodDecl *getNSNumberFactoryMethod(Sema &S, SourceLocation Loc,
+                                                QualType NumberType,
+                                                bool isLiteral = false,
+                                                SourceRange R = SourceRange()) {
+  Optional<NSAPI::NSNumberLiteralMethodKind> Kind =
+      S.NSAPIObj->getNSNumberFactoryMethodKind(NumberType);
+
+  if (!Kind) {
+    if (isLiteral) {
+      S.Diag(Loc, diag::err_invalid_nsnumber_type)
+        << NumberType << R;
+    }
+    return nullptr;
+  }
+
+  // If we already looked up this method, we're done.
+  if (S.NSNumberLiteralMethods[*Kind])
+    return S.NSNumberLiteralMethods[*Kind];
+
+  Selector Sel = S.NSAPIObj->getNSNumberLiteralSelector(*Kind,
+                                                        /*Instance=*/false);
+
+  ASTContext &CX = S.Context;
+
+  // Look up the NSNumber class, if we haven't done so already. It's cached
+  // in the Sema instance.
+  if (!S.NSNumberDecl) {
+    S.NSNumberDecl = LookupObjCInterfaceDeclForLiteral(S, Loc,
+                                                       Sema::LK_Numeric);
+    if (!S.NSNumberDecl) {
+      return nullptr;
+    }
+  }
+
+  if (S.NSNumberPointer.isNull()) {
+    // generate the pointer to NSNumber type.
+    QualType NSNumberObject = CX.getObjCInterfaceType(S.NSNumberDecl);
+    S.NSNumberPointer = CX.getObjCObjectPointerType(NSNumberObject);
+  }
+
+  // Look for the appropriate method within NSNumber.
+  ObjCMethodDecl *Method = S.NSNumberDecl->lookupClassMethod(Sel);
+  if (!Method && S.getLangOpts().DebuggerObjCLiteral) {
+    // create a stub definition this NSNumber factory method.
+    TypeSourceInfo *ReturnTInfo = nullptr;
+    Method =
+        ObjCMethodDecl::Create(CX, SourceLocation(), SourceLocation(), Sel,
+                               S.NSNumberPointer, ReturnTInfo, S.NSNumberDecl,
+                               /*isInstance=*/false, /*isVariadic=*/false,
+                               /*isPropertyAccessor=*/false,
+                               /*isSynthesizedAccessorStub=*/false,
+                               /*isImplicitlyDeclared=*/true,
+                               /*isDefined=*/false, ObjCMethodDecl::Required,
+                               /*HasRelatedResultType=*/false);
+    ParmVarDecl *value = ParmVarDecl::Create(S.Context, Method,
+                                             SourceLocation(), SourceLocation(),
+                                             &CX.Idents.get("value"),
+                                             NumberType, /*TInfo=*/nullptr,
+                                             SC_None, nullptr);
+    Method->setMethodParams(S.Context, value, None);
+  }
+
+  if (!validateBoxingMethod(S, Loc, S.NSNumberDecl, Sel, Method))
+    return nullptr;
+
+  // Note: if the parameter type is out-of-line, we'll catch it later in the
+  // implicit conversion.
+
+  S.NSNumberLiteralMethods[*Kind] = Method;
+  return Method;
+}
+
+/// BuildObjCNumericLiteral - builds an ObjCBoxedExpr AST node for the
+/// numeric literal expression. Type of the expression will be "NSNumber *".
+ExprResult Sema::BuildObjCNumericLiteral(SourceLocation AtLoc, Expr *Number) {
+  // Determine the type of the literal.
+  QualType NumberType = Number->getType();
+  if (CharacterLiteral *Char = dyn_cast<CharacterLiteral>(Number)) {
+    // In C, character literals have type 'int'. That's not the type we want
+    // to use to determine the Objective-c literal kind.
+    switch (Char->getKind()) {
+    case CharacterLiteral::Ascii:
+    case CharacterLiteral::UTF8:
+      NumberType = Context.CharTy;
+      break;
+
+    case CharacterLiteral::Wide:
+      NumberType = Context.getWideCharType();
+      break;
+
+    case CharacterLiteral::UTF16:
+      NumberType = Context.Char16Ty;
+      break;
+
+    case CharacterLiteral::UTF32:
+      NumberType = Context.Char32Ty;
+      break;
+    }
+  }
+
+  // Look for the appropriate method within NSNumber.
+  // Construct the literal.
+  SourceRange NR(Number->getSourceRange());
+  ObjCMethodDecl *Method = getNSNumberFactoryMethod(*this, AtLoc, NumberType,
+                                                    true, NR);
+  if (!Method)
+    return ExprError();
+
+  // Convert the number to the type that the parameter expects.
+  ParmVarDecl *ParamDecl = Method->parameters()[0];
+  InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
+                                                                    ParamDecl);
+  ExprResult ConvertedNumber = PerformCopyInitialization(Entity,
+                                                         SourceLocation(),
+                                                         Number);
+  if (ConvertedNumber.isInvalid())
+    return ExprError();
+  Number = ConvertedNumber.get();
+
+  // Use the effective source range of the literal, including the leading '@'.
+  return MaybeBindToTemporary(
+           new (Context) ObjCBoxedExpr(Number, NSNumberPointer, Method,
+                                       SourceRange(AtLoc, NR.getEnd())));
+}
+
+ExprResult Sema::ActOnObjCBoolLiteral(SourceLocation AtLoc,
+                                      SourceLocation ValueLoc,
+                                      bool Value) {
+  ExprResult Inner;
+  if (getLangOpts().CPlusPlus) {
+    Inner = ActOnCXXBoolLiteral(ValueLoc, Value? tok::kw_true : tok::kw_false);
+  } else {
+    // C doesn't actually have a way to represent literal values of type
+    // _Bool. So, we'll use 0/1 and implicit cast to _Bool.
+    Inner = ActOnIntegerConstant(ValueLoc, Value? 1 : 0);
+    Inner = ImpCastExprToType(Inner.get(), Context.BoolTy,
+                              CK_IntegralToBoolean);
+  }
+
+  return BuildObjCNumericLiteral(AtLoc, Inner.get());
+}
+
+/// Check that the given expression is a valid element of an Objective-C
+/// collection literal.
+static ExprResult CheckObjCCollectionLiteralElement(Sema &S, Expr *Element,
+                                                    QualType T,
+                                                    bool ArrayLiteral = false) {
+  // If the expression is type-dependent, there's nothing for us to do.
+  if (Element->isTypeDependent())
+    return Element;
+
+  ExprResult Result = S.CheckPlaceholderExpr(Element);
+  if (Result.isInvalid())
+    return ExprError();
+  Element = Result.get();
+
+  // In C++, check for an implicit conversion to an Objective-C object pointer
+  // type.
+  if (S.getLangOpts().CPlusPlus && Element->getType()->isRecordType()) {
+    InitializedEntity Entity
+      = InitializedEntity::InitializeParameter(S.Context, T,
+                                               /*Consumed=*/false);
+    InitializationKind Kind = InitializationKind::CreateCopy(
+        Element->getBeginLoc(), SourceLocation());
+    InitializationSequence Seq(S, Entity, Kind, Element);
+    if (!Seq.Failed())
+      return Seq.Perform(S, Entity, Kind, Element);
+  }
+
+  Expr *OrigElement = Element;
+
+  // Perform lvalue-to-rvalue conversion.
+  Result = S.DefaultLvalueConversion(Element);
+  if (Result.isInvalid())
+    return ExprError();
+  Element = Result.get();
+
+  // Make sure that we have an Objective-C pointer type or block.
+  if (!Element->getType()->isObjCObjectPointerType() &&
+      !Element->getType()->isBlockPointerType()) {
+    bool Recovered = false;
+
+    // If this is potentially an Objective-C numeric literal, add the '@'.
+    if (isa<IntegerLiteral>(OrigElement) ||
+        isa<CharacterLiteral>(OrigElement) ||
+        isa<FloatingLiteral>(OrigElement) ||
+        isa<ObjCBoolLiteralExpr>(OrigElement) ||
+        isa<CXXBoolLiteralExpr>(OrigElement)) {
+      if (S.NSAPIObj->getNSNumberFactoryMethodKind(OrigElement->getType())) {
+        int Which = isa<CharacterLiteral>(OrigElement) ? 1
+                  : (isa<CXXBoolLiteralExpr>(OrigElement) ||
+                     isa<ObjCBoolLiteralExpr>(OrigElement)) ? 2
+                  : 3;
+
+        S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
+            << Which << OrigElement->getSourceRange()
+            << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
+
+        Result =
+            S.BuildObjCNumericLiteral(OrigElement->getBeginLoc(), OrigElement);
+        if (Result.isInvalid())
+          return ExprError();
+
+        Element = Result.get();
+        Recovered = true;
+      }
+    }
+    // If this is potentially an Objective-C string literal, add the '@'.
+    else if (StringLiteral *String = dyn_cast<StringLiteral>(OrigElement)) {
+      if (String->isAscii()) {
+        S.Diag(OrigElement->getBeginLoc(), diag::err_box_literal_collection)
+            << 0 << OrigElement->getSourceRange()
+            << FixItHint::CreateInsertion(OrigElement->getBeginLoc(), "@");
+
+        Result = S.BuildObjCStringLiteral(OrigElement->getBeginLoc(), String);
+        if (Result.isInvalid())
+          return ExprError();
+
+        Element = Result.get();
+        Recovered = true;
+      }
+    }
+
+    if (!Recovered) {
+      S.Diag(Element->getBeginLoc(), diag::err_invalid_collection_element)
+          << Element->getType();
+      return ExprError();
+    }
+  }
+  if (ArrayLiteral)
+    if (ObjCStringLiteral *getString =
+          dyn_cast<ObjCStringLiteral>(OrigElement)) {
+      if (StringLiteral *SL = getString->getString()) {
+        unsigned numConcat = SL->getNumConcatenated();
+        if (numConcat > 1) {
+          // Only warn if the concatenated string doesn't come from a macro.
+          bool hasMacro = false;
+          for (unsigned i = 0; i < numConcat ; ++i)
+            if (SL->getStrTokenLoc(i).isMacroID()) {
+              hasMacro = true;
+              break;
+            }
+          if (!hasMacro)
+            S.Diag(Element->getBeginLoc(),
+                   diag::warn_concatenated_nsarray_literal)
+                << Element->getType();
+        }
+      }
+    }
+
+  // Make sure that the element has the type that the container factory
+  // function expects.
+  return S.PerformCopyInitialization(
+      InitializedEntity::InitializeParameter(S.Context, T,
+                                             /*Consumed=*/false),
+      Element->getBeginLoc(), Element);
+}
+
+ExprResult Sema::BuildObjCBoxedExpr(SourceRange SR, Expr *ValueExpr) {
+  if (ValueExpr->isTypeDependent()) {
+    ObjCBoxedExpr *BoxedExpr =
+      new (Context) ObjCBoxedExpr(ValueExpr, Context.DependentTy, nullptr, SR);
+    return BoxedExpr;
+  }
+  ObjCMethodDecl *BoxingMethod = nullptr;
+  QualType BoxedType;
+  // Convert the expression to an RValue, so we can check for pointer types...
+  ExprResult RValue = DefaultFunctionArrayLvalueConversion(ValueExpr);
+  if (RValue.isInvalid()) {
+    return ExprError();
+  }
+  SourceLocation Loc = SR.getBegin();
+  ValueExpr = RValue.get();
+  QualType ValueType(ValueExpr->getType());
+  if (const PointerType *PT = ValueType->getAs<PointerType>()) {
+    QualType PointeeType = PT->getPointeeType();
+    if (Context.hasSameUnqualifiedType(PointeeType, Context.CharTy)) {
+
+      if (!NSStringDecl) {
+        NSStringDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
+                                                         Sema::LK_String);
+        if (!NSStringDecl) {
+          return ExprError();
+        }
+        QualType NSStringObject = Context.getObjCInterfaceType(NSStringDecl);
+        NSStringPointer = Context.getObjCObjectPointerType(NSStringObject);
+      }
+
+      // The boxed expression can be emitted as a compile time constant if it is
+      // a string literal whose character encoding is compatible with UTF-8.
+      if (auto *CE = dyn_cast<ImplicitCastExpr>(ValueExpr))
+        if (CE->getCastKind() == CK_ArrayToPointerDecay)
+          if (auto *SL =
+                  dyn_cast<StringLiteral>(CE->getSubExpr()->IgnoreParens())) {
+            assert((SL->isAscii() || SL->isUTF8()) &&
+                   "unexpected character encoding");
+            StringRef Str = SL->getString();
+            const llvm::UTF8 *StrBegin = Str.bytes_begin();
+            const llvm::UTF8 *StrEnd = Str.bytes_end();
+            // Check that this is a valid UTF-8 string.
+            if (llvm::isLegalUTF8String(&StrBegin, StrEnd)) {
+              BoxedType = Context.getAttributedType(
+                  AttributedType::getNullabilityAttrKind(
+                      NullabilityKind::NonNull),
+                  NSStringPointer, NSStringPointer);
+              return new (Context) ObjCBoxedExpr(CE, BoxedType, nullptr, SR);
+            }
+
+            Diag(SL->getBeginLoc(), diag::warn_objc_boxing_invalid_utf8_string)
+                << NSStringPointer << SL->getSourceRange();
+          }
+
+      if (!StringWithUTF8StringMethod) {
+        IdentifierInfo *II = &Context.Idents.get("stringWithUTF8String");
+        Selector stringWithUTF8String = Context.Selectors.getUnarySelector(II);
+
+        // Look for the appropriate method within NSString.
+        BoxingMethod = NSStringDecl->lookupClassMethod(stringWithUTF8String);
+        if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
+          // Debugger needs to work even if NSString hasn't been defined.
+          TypeSourceInfo *ReturnTInfo = nullptr;
+          ObjCMethodDecl *M = ObjCMethodDecl::Create(
+              Context, SourceLocation(), SourceLocation(), stringWithUTF8String,
+              NSStringPointer, ReturnTInfo, NSStringDecl,
+              /*isInstance=*/false, /*isVariadic=*/false,
+              /*isPropertyAccessor=*/false,
+              /*isSynthesizedAccessorStub=*/false,
+              /*isImplicitlyDeclared=*/true,
+              /*isDefined=*/false, ObjCMethodDecl::Required,
+              /*HasRelatedResultType=*/false);
+          QualType ConstCharType = Context.CharTy.withConst();
+          ParmVarDecl *value =
+            ParmVarDecl::Create(Context, M,
+                                SourceLocation(), SourceLocation(),
+                                &Context.Idents.get("value"),
+                                Context.getPointerType(ConstCharType),
+                                /*TInfo=*/nullptr,
+                                SC_None, nullptr);
+          M->setMethodParams(Context, value, None);
+          BoxingMethod = M;
+        }
+
+        if (!validateBoxingMethod(*this, Loc, NSStringDecl,
+                                  stringWithUTF8String, BoxingMethod))
+           return ExprError();
+
+        StringWithUTF8StringMethod = BoxingMethod;
+      }
+
+      BoxingMethod = StringWithUTF8StringMethod;
+      BoxedType = NSStringPointer;
+      // Transfer the nullability from method's return type.
+      Optional<NullabilityKind> Nullability =
+          BoxingMethod->getReturnType()->getNullability(Context);
+      if (Nullability)
+        BoxedType = Context.getAttributedType(
+            AttributedType::getNullabilityAttrKind(*Nullability), BoxedType,
+            BoxedType);
+    }
+  } else if (ValueType->isBuiltinType()) {
+    // The other types we support are numeric, char and BOOL/bool. We could also
+    // provide limited support for structure types, such as NSRange, NSRect, and
+    // NSSize. See NSValue (NSValueGeometryExtensions) in <Foundation/NSGeometry.h>
+    // for more details.
+
+    // Check for a top-level character literal.
+    if (const CharacterLiteral *Char =
+        dyn_cast<CharacterLiteral>(ValueExpr->IgnoreParens())) {
+      // In C, character literals have type 'int'. That's not the type we want
+      // to use to determine the Objective-c literal kind.
+      switch (Char->getKind()) {
+      case CharacterLiteral::Ascii:
+      case CharacterLiteral::UTF8:
+        ValueType = Context.CharTy;
+        break;
+
+      case CharacterLiteral::Wide:
+        ValueType = Context.getWideCharType();
+        break;
+
+      case CharacterLiteral::UTF16:
+        ValueType = Context.Char16Ty;
+        break;
+
+      case CharacterLiteral::UTF32:
+        ValueType = Context.Char32Ty;
+        break;
+      }
+    }
+    // FIXME:  Do I need to do anything special with BoolTy expressions?
+
+    // Look for the appropriate method within NSNumber.
+    BoxingMethod = getNSNumberFactoryMethod(*this, Loc, ValueType);
+    BoxedType = NSNumberPointer;
+  } else if (const EnumType *ET = ValueType->getAs<EnumType>()) {
+    if (!ET->getDecl()->isComplete()) {
+      Diag(Loc, diag::err_objc_incomplete_boxed_expression_type)
+        << ValueType << ValueExpr->getSourceRange();
+      return ExprError();
+    }
+
+    BoxingMethod = getNSNumberFactoryMethod(*this, Loc,
+                                            ET->getDecl()->getIntegerType());
+    BoxedType = NSNumberPointer;
+  } else if (ValueType->isObjCBoxableRecordType()) {
+    // Support for structure types, that marked as objc_boxable
+    // struct __attribute__((objc_boxable)) s { ... };
+
+    // Look up the NSValue class, if we haven't done so already. It's cached
+    // in the Sema instance.
+    if (!NSValueDecl) {
+      NSValueDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
+                                                      Sema::LK_Boxed);
+      if (!NSValueDecl) {
+        return ExprError();
+      }
+
+      // generate the pointer to NSValue type.
+      QualType NSValueObject = Context.getObjCInterfaceType(NSValueDecl);
+      NSValuePointer = Context.getObjCObjectPointerType(NSValueObject);
+    }
+
+    if (!ValueWithBytesObjCTypeMethod) {
+      IdentifierInfo *II[] = {
+        &Context.Idents.get("valueWithBytes"),
+        &Context.Idents.get("objCType")
+      };
+      Selector ValueWithBytesObjCType = Context.Selectors.getSelector(2, II);
+
+      // Look for the appropriate method within NSValue.
+      BoxingMethod = NSValueDecl->lookupClassMethod(ValueWithBytesObjCType);
+      if (!BoxingMethod && getLangOpts().DebuggerObjCLiteral) {
+        // Debugger needs to work even if NSValue hasn't been defined.
+        TypeSourceInfo *ReturnTInfo = nullptr;
+        ObjCMethodDecl *M = ObjCMethodDecl::Create(
+            Context, SourceLocation(), SourceLocation(), ValueWithBytesObjCType,
+            NSValuePointer, ReturnTInfo, NSValueDecl,
+            /*isInstance=*/false,
+            /*isVariadic=*/false,
+            /*isPropertyAccessor=*/false,
+            /*isSynthesizedAccessorStub=*/false,
+            /*isImplicitlyDeclared=*/true,
+            /*isDefined=*/false, ObjCMethodDecl::Required,
+            /*HasRelatedResultType=*/false);
+
+        SmallVector<ParmVarDecl *, 2> Params;
+
+        ParmVarDecl *bytes =
+        ParmVarDecl::Create(Context, M,
+                            SourceLocation(), SourceLocation(),
+                            &Context.Idents.get("bytes"),
+                            Context.VoidPtrTy.withConst(),
+                            /*TInfo=*/nullptr,
+                            SC_None, nullptr);
+        Params.push_back(bytes);
+
+        QualType ConstCharType = Context.CharTy.withConst();
+        ParmVarDecl *type =
+        ParmVarDecl::Create(Context, M,
+                            SourceLocation(), SourceLocation(),
+                            &Context.Idents.get("type"),
+                            Context.getPointerType(ConstCharType),
+                            /*TInfo=*/nullptr,
+                            SC_None, nullptr);
+        Params.push_back(type);
+
+        M->setMethodParams(Context, Params, None);
+        BoxingMethod = M;
+      }
+
+      if (!validateBoxingMethod(*this, Loc, NSValueDecl,
+                                ValueWithBytesObjCType, BoxingMethod))
+        return ExprError();
+
+      ValueWithBytesObjCTypeMethod = BoxingMethod;
+    }
+
+    if (!ValueType.isTriviallyCopyableType(Context)) {
+      Diag(Loc, diag::err_objc_non_trivially_copyable_boxed_expression_type)
+        << ValueType << ValueExpr->getSourceRange();
+      return ExprError();
+    }
+
+    BoxingMethod = ValueWithBytesObjCTypeMethod;
+    BoxedType = NSValuePointer;
+  }
+
+  if (!BoxingMethod) {
+    Diag(Loc, diag::err_objc_illegal_boxed_expression_type)
+      << ValueType << ValueExpr->getSourceRange();
+    return ExprError();
+  }
+
+  DiagnoseUseOfDecl(BoxingMethod, Loc);
+
+  ExprResult ConvertedValueExpr;
+  if (ValueType->isObjCBoxableRecordType()) {
+    InitializedEntity IE = InitializedEntity::InitializeTemporary(ValueType);
+    ConvertedValueExpr = PerformCopyInitialization(IE, ValueExpr->getExprLoc(),
+                                                   ValueExpr);
+  } else {
+    // Convert the expression to the type that the parameter requires.
+    ParmVarDecl *ParamDecl = BoxingMethod->parameters()[0];
+    InitializedEntity IE = InitializedEntity::InitializeParameter(Context,
+                                                                  ParamDecl);
+    ConvertedValueExpr = PerformCopyInitialization(IE, SourceLocation(),
+                                                   ValueExpr);
+  }
+
+  if (ConvertedValueExpr.isInvalid())
+    return ExprError();
+  ValueExpr = ConvertedValueExpr.get();
+
+  ObjCBoxedExpr *BoxedExpr =
+    new (Context) ObjCBoxedExpr(ValueExpr, BoxedType,
+                                      BoxingMethod, SR);
+  return MaybeBindToTemporary(BoxedExpr);
+}
+
+/// Build an ObjC subscript pseudo-object expression, given that
+/// that's supported by the runtime.
+ExprResult Sema::BuildObjCSubscriptExpression(SourceLocation RB, Expr *BaseExpr,
+                                        Expr *IndexExpr,
+                                        ObjCMethodDecl *getterMethod,
+                                        ObjCMethodDecl *setterMethod) {
+  assert(!LangOpts.isSubscriptPointerArithmetic());
+
+  // We can't get dependent types here; our callers should have
+  // filtered them out.
+  assert((!BaseExpr->isTypeDependent() && !IndexExpr->isTypeDependent()) &&
+         "base or index cannot have dependent type here");
+
+  // Filter out placeholders in the index.  In theory, overloads could
+  // be preserved here, although that might not actually work correctly.
+  ExprResult Result = CheckPlaceholderExpr(IndexExpr);
+  if (Result.isInvalid())
+    return ExprError();
+  IndexExpr = Result.get();
+
+  // Perform lvalue-to-rvalue conversion on the base.
+  Result = DefaultLvalueConversion(BaseExpr);
+  if (Result.isInvalid())
+    return ExprError();
+  BaseExpr = Result.get();
+
+  // Build the pseudo-object expression.
+  return new (Context) ObjCSubscriptRefExpr(
+      BaseExpr, IndexExpr, Context.PseudoObjectTy, VK_LValue, OK_ObjCSubscript,
+      getterMethod, setterMethod, RB);
+}
+
+ExprResult Sema::BuildObjCArrayLiteral(SourceRange SR, MultiExprArg Elements) {
+  SourceLocation Loc = SR.getBegin();
+
+  if (!NSArrayDecl) {
+    NSArrayDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
+                                                    Sema::LK_Array);
+    if (!NSArrayDecl) {
+      return ExprError();
+    }
+  }
+
+  // Find the arrayWithObjects:count: method, if we haven't done so already.
+  QualType IdT = Context.getObjCIdType();
+  if (!ArrayWithObjectsMethod) {
+    Selector
+      Sel = NSAPIObj->getNSArraySelector(NSAPI::NSArr_arrayWithObjectsCount);
+    ObjCMethodDecl *Method = NSArrayDecl->lookupClassMethod(Sel);
+    if (!Method && getLangOpts().DebuggerObjCLiteral) {
+      TypeSourceInfo *ReturnTInfo = nullptr;
+      Method = ObjCMethodDecl::Create(
+          Context, SourceLocation(), SourceLocation(), Sel, IdT, ReturnTInfo,
+          Context.getTranslationUnitDecl(), false /*Instance*/,
+          false /*isVariadic*/,
+          /*isPropertyAccessor=*/false, /*isSynthesizedAccessorStub=*/false,
+          /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
+          ObjCMethodDecl::Required, false);
+      SmallVector<ParmVarDecl *, 2> Params;
+      ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
+                                                 SourceLocation(),
+                                                 SourceLocation(),
+                                                 &Context.Idents.get("objects"),
+                                                 Context.getPointerType(IdT),
+                                                 /*TInfo=*/nullptr,
+                                                 SC_None, nullptr);
+      Params.push_back(objects);
+      ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
+                                             SourceLocation(),
+                                             SourceLocation(),
+                                             &Context.Idents.get("cnt"),
+                                             Context.UnsignedLongTy,
+                                             /*TInfo=*/nullptr, SC_None,
+                                             nullptr);
+      Params.push_back(cnt);
+      Method->setMethodParams(Context, Params, None);
+    }
+
+    if (!validateBoxingMethod(*this, Loc, NSArrayDecl, Sel, Method))
+      return ExprError();
+
+    // Dig out the type that all elements should be converted to.
+    QualType T = Method->parameters()[0]->getType();
+    const PointerType *PtrT = T->getAs<PointerType>();
+    if (!PtrT ||
+        !Context.hasSameUnqualifiedType(PtrT->getPointeeType(), IdT)) {
+      Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
+        << Sel;
+      Diag(Method->parameters()[0]->getLocation(),
+           diag::note_objc_literal_method_param)
+        << 0 << T
+        << Context.getPointerType(IdT.withConst());
+      return ExprError();
+    }
+
+    // Check that the 'count' parameter is integral.
+    if (!Method->parameters()[1]->getType()->isIntegerType()) {
+      Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
+        << Sel;
+      Diag(Method->parameters()[1]->getLocation(),
+           diag::note_objc_literal_method_param)
+        << 1
+        << Method->parameters()[1]->getType()
+        << "integral";
+      return ExprError();
+    }
+
+    // We've found a good +arrayWithObjects:count: method. Save it!
+    ArrayWithObjectsMethod = Method;
+  }
+
+  QualType ObjectsType = ArrayWithObjectsMethod->parameters()[0]->getType();
+  QualType RequiredType = ObjectsType->castAs<PointerType>()->getPointeeType();
+
+  // Check that each of the elements provided is valid in a collection literal,
+  // performing conversions as necessary.
+  Expr **ElementsBuffer = Elements.data();
+  for (unsigned I = 0, N = Elements.size(); I != N; ++I) {
+    ExprResult Converted = CheckObjCCollectionLiteralElement(*this,
+                                                             ElementsBuffer[I],
+                                                             RequiredType, true);
+    if (Converted.isInvalid())
+      return ExprError();
+
+    ElementsBuffer[I] = Converted.get();
+  }
+
+  QualType Ty
+    = Context.getObjCObjectPointerType(
+                                    Context.getObjCInterfaceType(NSArrayDecl));
+
+  return MaybeBindToTemporary(
+           ObjCArrayLiteral::Create(Context, Elements, Ty,
+                                    ArrayWithObjectsMethod, SR));
+}
+
+/// Check for duplicate keys in an ObjC dictionary literal. For instance:
+///   NSDictionary *nd = @{ @"foo" : @"bar", @"foo" : @"baz" };
+static void
+CheckObjCDictionaryLiteralDuplicateKeys(Sema &S,
+                                        ObjCDictionaryLiteral *Literal) {
+  if (Literal->isValueDependent() || Literal->isTypeDependent())
+    return;
+
+  // NSNumber has quite relaxed equality semantics (for instance, @YES is
+  // considered equal to @1.0). For now, ignore floating points and just do a
+  // bit-width and sign agnostic integer compare.
+  struct APSIntCompare {
+    bool operator()(const llvm::APSInt &LHS, const llvm::APSInt &RHS) const {
+      return llvm::APSInt::compareValues(LHS, RHS) < 0;
+    }
+  };
+
+  llvm::DenseMap<StringRef, SourceLocation> StringKeys;
+  std::map<llvm::APSInt, SourceLocation, APSIntCompare> IntegralKeys;
+
+  auto checkOneKey = [&](auto &Map, const auto &Key, SourceLocation Loc) {
+    auto Pair = Map.insert({Key, Loc});
+    if (!Pair.second) {
+      S.Diag(Loc, diag::warn_nsdictionary_duplicate_key);
+      S.Diag(Pair.first->second, diag::note_nsdictionary_duplicate_key_here);
+    }
+  };
+
+  for (unsigned Idx = 0, End = Literal->getNumElements(); Idx != End; ++Idx) {
+    Expr *Key = Literal->getKeyValueElement(Idx).Key->IgnoreParenImpCasts();
+
+    if (auto *StrLit = dyn_cast<ObjCStringLiteral>(Key)) {
+      StringRef Bytes = StrLit->getString()->getBytes();
+      SourceLocation Loc = StrLit->getExprLoc();
+      checkOneKey(StringKeys, Bytes, Loc);
+    }
+
+    if (auto *BE = dyn_cast<ObjCBoxedExpr>(Key)) {
+      Expr *Boxed = BE->getSubExpr();
+      SourceLocation Loc = BE->getExprLoc();
+
+      // Check for @("foo").
+      if (auto *Str = dyn_cast<StringLiteral>(Boxed->IgnoreParenImpCasts())) {
+        checkOneKey(StringKeys, Str->getBytes(), Loc);
+        continue;
+      }
+
+      Expr::EvalResult Result;
+      if (Boxed->EvaluateAsInt(Result, S.getASTContext(),
+                               Expr::SE_AllowSideEffects)) {
+        checkOneKey(IntegralKeys, Result.Val.getInt(), Loc);
+      }
+    }
+  }
+}
+
+ExprResult Sema::BuildObjCDictionaryLiteral(SourceRange SR,
+                              MutableArrayRef<ObjCDictionaryElement> Elements) {
+  SourceLocation Loc = SR.getBegin();
+
+  if (!NSDictionaryDecl) {
+    NSDictionaryDecl = LookupObjCInterfaceDeclForLiteral(*this, Loc,
+                                                         Sema::LK_Dictionary);
+    if (!NSDictionaryDecl) {
+      return ExprError();
+    }
+  }
+
+  // Find the dictionaryWithObjects:forKeys:count: method, if we haven't done
+  // so already.
+  QualType IdT = Context.getObjCIdType();
+  if (!DictionaryWithObjectsMethod) {
+    Selector Sel = NSAPIObj->getNSDictionarySelector(
+                               NSAPI::NSDict_dictionaryWithObjectsForKeysCount);
+    ObjCMethodDecl *Method = NSDictionaryDecl->lookupClassMethod(Sel);
+    if (!Method && getLangOpts().DebuggerObjCLiteral) {
+      Method = ObjCMethodDecl::Create(
+          Context, SourceLocation(), SourceLocation(), Sel, IdT,
+          nullptr /*TypeSourceInfo */, Context.getTranslationUnitDecl(),
+          false /*Instance*/, false /*isVariadic*/,
+          /*isPropertyAccessor=*/false,
+          /*isSynthesizedAccessorStub=*/false,
+          /*isImplicitlyDeclared=*/true, /*isDefined=*/false,
+          ObjCMethodDecl::Required, false);
+      SmallVector<ParmVarDecl *, 3> Params;
+      ParmVarDecl *objects = ParmVarDecl::Create(Context, Method,
+                                                 SourceLocation(),
+                                                 SourceLocation(),
+                                                 &Context.Idents.get("objects"),
+                                                 Context.getPointerType(IdT),
+                                                 /*TInfo=*/nullptr, SC_None,
+                                                 nullptr);
+      Params.push_back(objects);
+      ParmVarDecl *keys = ParmVarDecl::Create(Context, Method,
+                                              SourceLocation(),
+                                              SourceLocation(),
+                                              &Context.Idents.get("keys"),
+                                              Context.getPointerType(IdT),
+                                              /*TInfo=*/nullptr, SC_None,
+                                              nullptr);
+      Params.push_back(keys);
+      ParmVarDecl *cnt = ParmVarDecl::Create(Context, Method,
+                                             SourceLocation(),
+                                             SourceLocation(),
+                                             &Context.Idents.get("cnt"),
+                                             Context.UnsignedLongTy,
+                                             /*TInfo=*/nullptr, SC_None,
+                                             nullptr);
+      Params.push_back(cnt);
+      Method->setMethodParams(Context, Params, None);
+    }
+
+    if (!validateBoxingMethod(*this, SR.getBegin(), NSDictionaryDecl, Sel,
+                              Method))
+       return ExprError();
+
+    // Dig out the type that all values should be converted to.
+    QualType ValueT = Method->parameters()[0]->getType();
+    const PointerType *PtrValue = ValueT->getAs<PointerType>();
+    if (!PtrValue ||
+        !Context.hasSameUnqualifiedType(PtrValue->getPointeeType(), IdT)) {
+      Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
+        << Sel;
+      Diag(Method->parameters()[0]->getLocation(),
+           diag::note_objc_literal_method_param)
+        << 0 << ValueT
+        << Context.getPointerType(IdT.withConst());
+      return ExprError();
+    }
+
+    // Dig out the type that all keys should be converted to.
+    QualType KeyT = Method->parameters()[1]->getType();
+    const PointerType *PtrKey = KeyT->getAs<PointerType>();
+    if (!PtrKey ||
+        !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
+                                        IdT)) {
+      bool err = true;
+      if (PtrKey) {
+        if (QIDNSCopying.isNull()) {
+          // key argument of selector is id<NSCopying>?
+          if (ObjCProtocolDecl *NSCopyingPDecl =
+              LookupProtocol(&Context.Idents.get("NSCopying"), SR.getBegin())) {
+            ObjCProtocolDecl *PQ[] = {NSCopyingPDecl};
+            QIDNSCopying =
+              Context.getObjCObjectType(Context.ObjCBuiltinIdTy, { },
+                                        llvm::makeArrayRef(
+                                          (ObjCProtocolDecl**) PQ,
+                                          1),
+                                        false);
+            QIDNSCopying = Context.getObjCObjectPointerType(QIDNSCopying);
+          }
+        }
+        if (!QIDNSCopying.isNull())
+          err = !Context.hasSameUnqualifiedType(PtrKey->getPointeeType(),
+                                                QIDNSCopying);
+      }
+
+      if (err) {
+        Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
+          << Sel;
+        Diag(Method->parameters()[1]->getLocation(),
+             diag::note_objc_literal_method_param)
+          << 1 << KeyT
+          << Context.getPointerType(IdT.withConst());
+        return ExprError();
+      }
+    }
+
+    // Check that the 'count' parameter is integral.
+    QualType CountType = Method->parameters()[2]->getType();
+    if (!CountType->isIntegerType()) {
+      Diag(SR.getBegin(), diag::err_objc_literal_method_sig)
+        << Sel;
+      Diag(Method->parameters()[2]->getLocation(),
+           diag::note_objc_literal_method_param)
+        << 2 << CountType
+        << "integral";
+      return ExprError();
+    }
+
+    // We've found a good +dictionaryWithObjects:keys:count: method; save it!
+    DictionaryWithObjectsMethod = Method;
+  }
+
+  QualType ValuesT = DictionaryWithObjectsMethod->parameters()[0]->getType();
+  QualType ValueT = ValuesT->castAs<PointerType>()->getPointeeType();
+  QualType KeysT = DictionaryWithObjectsMethod->parameters()[1]->getType();
+  QualType KeyT = KeysT->castAs<PointerType>()->getPointeeType();
+
+  // Check that each of the keys and values provided is valid in a collection
+  // literal, performing conversions as necessary.
+  bool HasPackExpansions = false;
+  for (ObjCDictionaryElement &Element : Elements) {
+    // Check the key.
+    ExprResult Key = CheckObjCCollectionLiteralElement(*this, Element.Key,
+                                                       KeyT);
+    if (Key.isInvalid())
+      return ExprError();
+
+    // Check the value.
+    ExprResult Value
+      = CheckObjCCollectionLiteralElement(*this, Element.Value, ValueT);
+    if (Value.isInvalid())
+      return ExprError();
+
+    Element.Key = Key.get();
+    Element.Value = Value.get();
+
+    if (Element.EllipsisLoc.isInvalid())
+      continue;
+
+    if (!Element.Key->containsUnexpandedParameterPack() &&
+        !Element.Value->containsUnexpandedParameterPack()) {
+      Diag(Element.EllipsisLoc,
+           diag::err_pack_expansion_without_parameter_packs)
+          << SourceRange(Element.Key->getBeginLoc(),
+                         Element.Value->getEndLoc());
+      return ExprError();
+    }
+
+    HasPackExpansions = true;
+  }
+
+  QualType Ty = Context.getObjCObjectPointerType(
+      Context.getObjCInterfaceType(NSDictionaryDecl));
+
+  auto *Literal =
+      ObjCDictionaryLiteral::Create(Context, Elements, HasPackExpansions, Ty,
+                                    DictionaryWithObjectsMethod, SR);
+  CheckObjCDictionaryLiteralDuplicateKeys(*this, Literal);
+  return MaybeBindToTemporary(Literal);
+}
+
+ExprResult Sema::BuildObjCEncodeExpression(SourceLocation AtLoc,
+                                      TypeSourceInfo *EncodedTypeInfo,
+                                      SourceLocation RParenLoc) {
+  QualType EncodedType = EncodedTypeInfo->getType();
+  QualType StrTy;
+  if (EncodedType->isDependentType())
+    StrTy = Context.DependentTy;
+  else {
+    if (!EncodedType->getAsArrayTypeUnsafe() && //// Incomplete array is handled.
+        !EncodedType->isVoidType()) // void is handled too.
+      if (RequireCompleteType(AtLoc, EncodedType,
+                              diag::err_incomplete_type_objc_at_encode,
+                              EncodedTypeInfo->getTypeLoc()))
+        return ExprError();
+
+    std::string Str;
+    QualType NotEncodedT;
+    Context.getObjCEncodingForType(EncodedType, Str, nullptr, &NotEncodedT);
+    if (!NotEncodedT.isNull())
+      Diag(AtLoc, diag::warn_incomplete_encoded_type)
+        << EncodedType << NotEncodedT;
+
+    // The type of @encode is the same as the type of the corresponding string,
+    // which is an array type.
+    StrTy = Context.getStringLiteralArrayType(Context.CharTy, Str.size());
+  }
+
+  return new (Context) ObjCEncodeExpr(StrTy, EncodedTypeInfo, AtLoc, RParenLoc);
+}
+
+ExprResult Sema::ParseObjCEncodeExpression(SourceLocation AtLoc,
+                                           SourceLocation EncodeLoc,
+                                           SourceLocation LParenLoc,
+                                           ParsedType ty,
+                                           SourceLocation RParenLoc) {
+  // FIXME: Preserve type source info ?
+  TypeSourceInfo *TInfo;
+  QualType EncodedType = GetTypeFromParser(ty, &TInfo);
+  if (!TInfo)
+    TInfo = Context.getTrivialTypeSourceInfo(EncodedType,
+                                             getLocForEndOfToken(LParenLoc));
+
+  return BuildObjCEncodeExpression(AtLoc, TInfo, RParenLoc);
+}
+
+static bool HelperToDiagnoseMismatchedMethodsInGlobalPool(Sema &S,
+                                               SourceLocation AtLoc,
+                                               SourceLocation LParenLoc,
+                                               SourceLocation RParenLoc,
+                                               ObjCMethodDecl *Method,
+                                               ObjCMethodList &MethList) {
+  ObjCMethodList *M = &MethList;
+  bool Warned = false;
+  for (M = M->getNext(); M; M=M->getNext()) {
+    ObjCMethodDecl *MatchingMethodDecl = M->getMethod();
+    if (MatchingMethodDecl == Method ||
+        isa<ObjCImplDecl>(MatchingMethodDecl->getDeclContext()) ||
+        MatchingMethodDecl->getSelector() != Method->getSelector())
+      continue;
+    if (!S.MatchTwoMethodDeclarations(Method,
+                                      MatchingMethodDecl, Sema::MMS_loose)) {
+      if (!Warned) {
+        Warned = true;
+        S.Diag(AtLoc, diag::warn_multiple_selectors)
+          << Method->getSelector() << FixItHint::CreateInsertion(LParenLoc, "(")
+          << FixItHint::CreateInsertion(RParenLoc, ")");
+        S.Diag(Method->getLocation(), diag::note_method_declared_at)
+          << Method->getDeclName();
+      }
+      S.Diag(MatchingMethodDecl->getLocation(), diag::note_method_declared_at)
+        << MatchingMethodDecl->getDeclName();
+    }
+  }
+  return Warned;
+}
+
+static void DiagnoseMismatchedSelectors(Sema &S, SourceLocation AtLoc,
+                                        ObjCMethodDecl *Method,
+                                        SourceLocation LParenLoc,
+                                        SourceLocation RParenLoc,
+                                        bool WarnMultipleSelectors) {
+  if (!WarnMultipleSelectors ||
+      S.Diags.isIgnored(diag::warn_multiple_selectors, SourceLocation()))
+    return;
+  bool Warned = false;
+  for (Sema::GlobalMethodPool::iterator b = S.MethodPool.begin(),
+       e = S.MethodPool.end(); b != e; b++) {
+    // first, instance methods
+    ObjCMethodList &InstMethList = b->second.first;
+    if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
+                                                      Method, InstMethList))
+      Warned = true;
+
+    // second, class methods
+    ObjCMethodList &ClsMethList = b->second.second;
+    if (HelperToDiagnoseMismatchedMethodsInGlobalPool(S, AtLoc, LParenLoc, RParenLoc,
+                                                      Method, ClsMethList) || Warned)
+      return;
+  }
+}
+
+static ObjCMethodDecl *LookupDirectMethodInMethodList(Sema &S, Selector Sel,
+                                                      ObjCMethodList &MethList,
+                                                      bool &onlyDirect,
+                                                      bool &anyDirect) {
+  (void)Sel;
+  ObjCMethodList *M = &MethList;
+  ObjCMethodDecl *DirectMethod = nullptr;
+  for (; M; M = M->getNext()) {
+    ObjCMethodDecl *Method = M->getMethod();
+    if (!Method)
+      continue;
+    assert(Method->getSelector() == Sel && "Method with wrong selector in method list");
+    if (Method->isDirectMethod()) {
+      anyDirect = true;
+      DirectMethod = Method;
+    } else
+      onlyDirect = false;
+  }
+
+  return DirectMethod;
+}
+
+// Search the global pool for (potentially) direct methods matching the given
+// selector. If a non-direct method is found, set \param onlyDirect to false. If
+// a direct method is found, set \param anyDirect to true. Returns a direct
+// method, if any.
+static ObjCMethodDecl *LookupDirectMethodInGlobalPool(Sema &S, Selector Sel,
+                                                      bool &onlyDirect,
+                                                      bool &anyDirect) {
+  auto Iter = S.MethodPool.find(Sel);
+  if (Iter == S.MethodPool.end())
+    return nullptr;
+
+  ObjCMethodDecl *DirectInstance = LookupDirectMethodInMethodList(
+      S, Sel, Iter->second.first, onlyDirect, anyDirect);
+  ObjCMethodDecl *DirectClass = LookupDirectMethodInMethodList(
+      S, Sel, Iter->second.second, onlyDirect, anyDirect);
+
+  return DirectInstance ? DirectInstance : DirectClass;
+}
+
+static ObjCMethodDecl *findMethodInCurrentClass(Sema &S, Selector Sel) {
+  auto *CurMD = S.getCurMethodDecl();
+  if (!CurMD)
+    return nullptr;
+  ObjCInterfaceDecl *IFace = CurMD->getClassInterface();
+
+  // The language enforce that only one direct method is present in a given
+  // class, so we just need to find one method in the current class to know
+  // whether Sel is potentially direct in this context.
+  if (ObjCMethodDecl *MD = IFace->lookupMethod(Sel, /*isInstance=*/true))
+    return MD;
+  if (ObjCMethodDecl *MD = IFace->lookupPrivateMethod(Sel, /*Instance=*/true))
+    return MD;
+  if (ObjCMethodDecl *MD = IFace->lookupMethod(Sel, /*isInstance=*/false))
+    return MD;
+  if (ObjCMethodDecl *MD = IFace->lookupPrivateMethod(Sel, /*Instance=*/false))
+    return MD;
+
+  return nullptr;
+}
+
+ExprResult Sema::ParseObjCSelectorExpression(Selector Sel,
+                                             SourceLocation AtLoc,
+                                             SourceLocation SelLoc,
+                                             SourceLocation LParenLoc,
+                                             SourceLocation RParenLoc,
+                                             bool WarnMultipleSelectors) {
+  ObjCMethodDecl *Method = LookupInstanceMethodInGlobalPool(Sel,
+                             SourceRange(LParenLoc, RParenLoc));
+  if (!Method)
+    Method = LookupFactoryMethodInGlobalPool(Sel,
+                                          SourceRange(LParenLoc, RParenLoc));
+  if (!Method) {
+    if (const ObjCMethodDecl *OM = SelectorsForTypoCorrection(Sel)) {
+      Selector MatchedSel = OM->getSelector();
+      SourceRange SelectorRange(LParenLoc.getLocWithOffset(1),
+                                RParenLoc.getLocWithOffset(-1));
+      Diag(SelLoc, diag::warn_undeclared_selector_with_typo)
+        << Sel << MatchedSel
+        << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
+
+    } else
+        Diag(SelLoc, diag::warn_undeclared_selector) << Sel;
+  } else {
+    DiagnoseMismatchedSelectors(*this, AtLoc, Method, LParenLoc, RParenLoc,
+                                WarnMultipleSelectors);
+
+    bool onlyDirect = true;
+    bool anyDirect = false;
+    ObjCMethodDecl *GlobalDirectMethod =
+        LookupDirectMethodInGlobalPool(*this, Sel, onlyDirect, anyDirect);
+
+    if (onlyDirect) {
+      Diag(AtLoc, diag::err_direct_selector_expression)
+          << Method->getSelector();
+      Diag(Method->getLocation(), diag::note_direct_method_declared_at)
+          << Method->getDeclName();
+    } else if (anyDirect) {
+      // If we saw any direct methods, see if we see a direct member of the
+      // current class. If so, the @selector will likely be used to refer to
+      // this direct method.
+      ObjCMethodDecl *LikelyTargetMethod = findMethodInCurrentClass(*this, Sel);
+      if (LikelyTargetMethod && LikelyTargetMethod->isDirectMethod()) {
+        Diag(AtLoc, diag::warn_potentially_direct_selector_expression) << Sel;
+        Diag(LikelyTargetMethod->getLocation(),
+             diag::note_direct_method_declared_at)
+            << LikelyTargetMethod->getDeclName();
+      } else if (!LikelyTargetMethod) {
+        // Otherwise, emit the "strict" variant of this diagnostic, unless
+        // LikelyTargetMethod is non-direct.
+        Diag(AtLoc, diag::warn_strict_potentially_direct_selector_expression)
+            << Sel;
+        Diag(GlobalDirectMethod->getLocation(),
+             diag::note_direct_method_declared_at)
+            << GlobalDirectMethod->getDeclName();
+      }
+    }
+  }
+
+  if (Method &&
+      Method->getImplementationControl() != ObjCMethodDecl::Optional &&
+      !getSourceManager().isInSystemHeader(Method->getLocation()))
+    ReferencedSelectors.insert(std::make_pair(Sel, AtLoc));
+
+  // In ARC, forbid the user from using @selector for
+  // retain/release/autorelease/dealloc/retainCount.
+  if (getLangOpts().ObjCAutoRefCount) {
+    switch (Sel.getMethodFamily()) {
+    case OMF_retain:
+    case OMF_release:
+    case OMF_autorelease:
+    case OMF_retainCount:
+    case OMF_dealloc:
+      Diag(AtLoc, diag::err_arc_illegal_selector) <<
+        Sel << SourceRange(LParenLoc, RParenLoc);
+      break;
+
+    case OMF_None:
+    case OMF_alloc:
+    case OMF_copy:
+    case OMF_finalize:
+    case OMF_init:
+    case OMF_mutableCopy:
+    case OMF_new:
+    case OMF_self:
+    case OMF_initialize:
+    case OMF_performSelector:
+      break;
+    }
+  }
+  QualType Ty = Context.getObjCSelType();
+  return new (Context) ObjCSelectorExpr(Ty, Sel, AtLoc, RParenLoc);
+}
+
+ExprResult Sema::ParseObjCProtocolExpression(IdentifierInfo *ProtocolId,
+                                             SourceLocation AtLoc,
+                                             SourceLocation ProtoLoc,
+                                             SourceLocation LParenLoc,
+                                             SourceLocation ProtoIdLoc,
+                                             SourceLocation RParenLoc) {
+  ObjCProtocolDecl* PDecl = LookupProtocol(ProtocolId, ProtoIdLoc);
+  if (!PDecl) {
+    Diag(ProtoLoc, diag::err_undeclared_protocol) << ProtocolId;
+    return true;
+  }
+  if (PDecl->isNonRuntimeProtocol())
+    Diag(ProtoLoc, diag::err_objc_non_runtime_protocol_in_protocol_expr)
+        << PDecl;
+  if (!PDecl->hasDefinition()) {
+    Diag(ProtoLoc, diag::err_atprotocol_protocol) << PDecl;
+    Diag(PDecl->getLocation(), diag::note_entity_declared_at) << PDecl;
+  } else {
+    PDecl = PDecl->getDefinition();
+  }
+
+  QualType Ty = Context.getObjCProtoType();
+  if (Ty.isNull())
+    return true;
+  Ty = Context.getObjCObjectPointerType(Ty);
+  return new (Context) ObjCProtocolExpr(Ty, PDecl, AtLoc, ProtoIdLoc, RParenLoc);
+}
+
+/// Try to capture an implicit reference to 'self'.
+ObjCMethodDecl *Sema::tryCaptureObjCSelf(SourceLocation Loc) {
+  DeclContext *DC = getFunctionLevelDeclContext();
+
+  // If we're not in an ObjC method, error out.  Note that, unlike the
+  // C++ case, we don't require an instance method --- class methods
+  // still have a 'self', and we really do still need to capture it!
+  ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(DC);
+  if (!method)
+    return nullptr;
+
+  tryCaptureVariable(method->getSelfDecl(), Loc);
+
+  return method;
+}
+
+static QualType stripObjCInstanceType(ASTContext &Context, QualType T) {
+  QualType origType = T;
+  if (auto nullability = AttributedType::stripOuterNullability(T)) {
+    if (T == Context.getObjCInstanceType()) {
+      return Context.getAttributedType(
+               AttributedType::getNullabilityAttrKind(*nullability),
+               Context.getObjCIdType(),
+               Context.getObjCIdType());
+    }
+
+    return origType;
+  }
+
+  if (T == Context.getObjCInstanceType())
+    return Context.getObjCIdType();
+
+  return origType;
+}
+
+/// Determine the result type of a message send based on the receiver type,
+/// method, and the kind of message send.
+///
+/// This is the "base" result type, which will still need to be adjusted
+/// to account for nullability.
+static QualType getBaseMessageSendResultType(Sema &S,
+                                             QualType ReceiverType,
+                                             ObjCMethodDecl *Method,
+                                             bool isClassMessage,
+                                             bool isSuperMessage) {
+  assert(Method && "Must have a method");
+  if (!Method->hasRelatedResultType())
+    return Method->getSendResultType(ReceiverType);
+
+  ASTContext &Context = S.Context;
+
+  // Local function that transfers the nullability of the method's
+  // result type to the returned result.
+  auto transferNullability = [&](QualType type) -> QualType {
+    // If the method's result type has nullability, extract it.
+    if (auto nullability = Method->getSendResultType(ReceiverType)
+                             ->getNullability(Context)){
+      // Strip off any outer nullability sugar from the provided type.
+      (void)AttributedType::stripOuterNullability(type);
+
+      // Form a new attributed type using the method result type's nullability.
+      return Context.getAttributedType(
+               AttributedType::getNullabilityAttrKind(*nullability),
+               type,
+               type);
+    }
+
+    return type;
+  };
+
+  // If a method has a related return type:
+  //   - if the method found is an instance method, but the message send
+  //     was a class message send, T is the declared return type of the method
+  //     found
+  if (Method->isInstanceMethod() && isClassMessage)
+    return stripObjCInstanceType(Context,
+                                 Method->getSendResultType(ReceiverType));
+
+  //   - if the receiver is super, T is a pointer to the class of the
+  //     enclosing method definition
+  if (isSuperMessage) {
+    if (ObjCMethodDecl *CurMethod = S.getCurMethodDecl())
+      if (ObjCInterfaceDecl *Class = CurMethod->getClassInterface()) {
+        return transferNullability(
+                 Context.getObjCObjectPointerType(
+                   Context.getObjCInterfaceType(Class)));
+      }
+  }
+
+  //   - if the receiver is the name of a class U, T is a pointer to U
+  if (ReceiverType->getAsObjCInterfaceType())
+    return transferNullability(Context.getObjCObjectPointerType(ReceiverType));
+  //   - if the receiver is of type Class or qualified Class type,
+  //     T is the declared return type of the method.
+  if (ReceiverType->isObjCClassType() ||
+      ReceiverType->isObjCQualifiedClassType())
+    return stripObjCInstanceType(Context,
+                                 Method->getSendResultType(ReceiverType));
+
+  //   - if the receiver is id, qualified id, Class, or qualified Class, T
+  //     is the receiver type, otherwise
+  //   - T is the type of the receiver expression.
+  return transferNullability(ReceiverType);
+}
+
+QualType Sema::getMessageSendResultType(const Expr *Receiver,
+                                        QualType ReceiverType,
+                                        ObjCMethodDecl *Method,
+                                        bool isClassMessage,
+                                        bool isSuperMessage) {
+  // Produce the result type.
+  QualType resultType = getBaseMessageSendResultType(*this, ReceiverType,
+                                                     Method,
+                                                     isClassMessage,
+                                                     isSuperMessage);
+
+  // If this is a class message, ignore the nullability of the receiver.
+  if (isClassMessage) {
+    // In a class method, class messages to 'self' that return instancetype can
+    // be typed as the current class.  We can safely do this in ARC because self
+    // can't be reassigned, and we do it unsafely outside of ARC because in
+    // practice people never reassign self in class methods and there's some
+    // virtue in not being aggressively pedantic.
+    if (Receiver && Receiver->isObjCSelfExpr()) {
+      assert(ReceiverType->isObjCClassType() && "expected a Class self");
+      QualType T = Method->getSendResultType(ReceiverType);
+      AttributedType::stripOuterNullability(T);
+      if (T == Context.getObjCInstanceType()) {
+        const ObjCMethodDecl *MD = cast<ObjCMethodDecl>(
+            cast<ImplicitParamDecl>(
+                cast<DeclRefExpr>(Receiver->IgnoreParenImpCasts())->getDecl())
+                ->getDeclContext());
+        assert(MD->isClassMethod() && "expected a class method");
+        QualType NewResultType = Context.getObjCObjectPointerType(
+            Context.getObjCInterfaceType(MD->getClassInterface()));
+        if (auto Nullability = resultType->getNullability(Context))
+          NewResultType = Context.getAttributedType(
+              AttributedType::getNullabilityAttrKind(*Nullability),
+              NewResultType, NewResultType);
+        return NewResultType;
+      }
+    }
+    return resultType;
+  }
+
+  // There is nothing left to do if the result type cannot have a nullability
+  // specifier.
+  if (!resultType->canHaveNullability())
+    return resultType;
+
+  // Map the nullability of the result into a table index.
+  unsigned receiverNullabilityIdx = 0;
+  if (Optional<NullabilityKind> nullability =
+          ReceiverType->getNullability(Context)) {
+    if (*nullability == NullabilityKind::NullableResult)
+      nullability = NullabilityKind::Nullable;
+    receiverNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
+  }
+
+  unsigned resultNullabilityIdx = 0;
+  if (Optional<NullabilityKind> nullability =
+          resultType->getNullability(Context)) {
+    if (*nullability == NullabilityKind::NullableResult)
+      nullability = NullabilityKind::Nullable;
+    resultNullabilityIdx = 1 + static_cast<unsigned>(*nullability);
+  }
+
+  // The table of nullability mappings, indexed by the receiver's nullability
+  // and then the result type's nullability.
+  static const uint8_t None = 0;
+  static const uint8_t NonNull = 1;
+  static const uint8_t Nullable = 2;
+  static const uint8_t Unspecified = 3;
+  static const uint8_t nullabilityMap[4][4] = {
+    //                  None        NonNull       Nullable    Unspecified
+    /* None */        { None,       None,         Nullable,   None },
+    /* NonNull */     { None,       NonNull,      Nullable,   Unspecified },
+    /* Nullable */    { Nullable,   Nullable,     Nullable,   Nullable },
+    /* Unspecified */ { None,       Unspecified,  Nullable,   Unspecified }
+  };
+
+  unsigned newResultNullabilityIdx
+    = nullabilityMap[receiverNullabilityIdx][resultNullabilityIdx];
+  if (newResultNullabilityIdx == resultNullabilityIdx)
+    return resultType;
+
+  // Strip off the existing nullability. This removes as little type sugar as
+  // possible.
+  do {
+    if (auto attributed = dyn_cast<AttributedType>(resultType.getTypePtr())) {
+      resultType = attributed->getModifiedType();
+    } else {
+      resultType = resultType.getDesugaredType(Context);
+    }
+  } while (resultType->getNullability(Context));
+
+  // Add nullability back if needed.
+  if (newResultNullabilityIdx > 0) {
+    auto newNullability
+      = static_cast<NullabilityKind>(newResultNullabilityIdx-1);
+    return Context.getAttributedType(
+             AttributedType::getNullabilityAttrKind(newNullability),
+             resultType, resultType);
+  }
+
+  return resultType;
+}
+
+/// Look for an ObjC method whose result type exactly matches the given type.
+static const ObjCMethodDecl *
+findExplicitInstancetypeDeclarer(const ObjCMethodDecl *MD,
+                                 QualType instancetype) {
+  if (MD->getReturnType() == instancetype)
+    return MD;
+
+  // For these purposes, a method in an @implementation overrides a
+  // declaration in the @interface.
+  if (const ObjCImplDecl *impl =
+        dyn_cast<ObjCImplDecl>(MD->getDeclContext())) {
+    const ObjCContainerDecl *iface;
+    if (const ObjCCategoryImplDecl *catImpl =
+          dyn_cast<ObjCCategoryImplDecl>(impl)) {
+      iface = catImpl->getCategoryDecl();
+    } else {
+      iface = impl->getClassInterface();
+    }
+
+    const ObjCMethodDecl *ifaceMD =
+      iface->getMethod(MD->getSelector(), MD->isInstanceMethod());
+    if (ifaceMD) return findExplicitInstancetypeDeclarer(ifaceMD, instancetype);
+  }
+
+  SmallVector<const ObjCMethodDecl *, 4> overrides;
+  MD->getOverriddenMethods(overrides);
+  for (unsigned i = 0, e = overrides.size(); i != e; ++i) {
+    if (const ObjCMethodDecl *result =
+          findExplicitInstancetypeDeclarer(overrides[i], instancetype))
+      return result;
+  }
+
+  return nullptr;
+}
+
+void Sema::EmitRelatedResultTypeNoteForReturn(QualType destType) {
+  // Only complain if we're in an ObjC method and the required return
+  // type doesn't match the method's declared return type.
+  ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(CurContext);
+  if (!MD || !MD->hasRelatedResultType() ||
+      Context.hasSameUnqualifiedType(destType, MD->getReturnType()))
+    return;
+
+  // Look for a method overridden by this method which explicitly uses
+  // 'instancetype'.
+  if (const ObjCMethodDecl *overridden =
+        findExplicitInstancetypeDeclarer(MD, Context.getObjCInstanceType())) {
+    SourceRange range = overridden->getReturnTypeSourceRange();
+    SourceLocation loc = range.getBegin();
+    if (loc.isInvalid())
+      loc = overridden->getLocation();
+    Diag(loc, diag::note_related_result_type_explicit)
+      << /*current method*/ 1 << range;
+    return;
+  }
+
+  // Otherwise, if we have an interesting method family, note that.
+  // This should always trigger if the above didn't.
+  if (ObjCMethodFamily family = MD->getMethodFamily())
+    Diag(MD->getLocation(), diag::note_related_result_type_family)
+      << /*current method*/ 1
+      << family;
+}
+
+void Sema::EmitRelatedResultTypeNote(const Expr *E) {
+  E = E->IgnoreParenImpCasts();
+  const ObjCMessageExpr *MsgSend = dyn_cast<ObjCMessageExpr>(E);
+  if (!MsgSend)
+    return;
+
+  const ObjCMethodDecl *Method = MsgSend->getMethodDecl();
+  if (!Method)
+    return;
+
+  if (!Method->hasRelatedResultType())
+    return;
+
+  if (Context.hasSameUnqualifiedType(
+          Method->getReturnType().getNonReferenceType(), MsgSend->getType()))
+    return;
+
+  if (!Context.hasSameUnqualifiedType(Method->getReturnType(),
+                                      Context.getObjCInstanceType()))
+    return;
+
+  Diag(Method->getLocation(), diag::note_related_result_type_inferred)
+    << Method->isInstanceMethod() << Method->getSelector()
+    << MsgSend->getType();
+}
+
+bool Sema::CheckMessageArgumentTypes(
+    const Expr *Receiver, QualType ReceiverType, MultiExprArg Args,
+    Selector Sel, ArrayRef<SourceLocation> SelectorLocs, ObjCMethodDecl *Method,
+    bool isClassMessage, bool isSuperMessage, SourceLocation lbrac,
+    SourceLocation rbrac, SourceRange RecRange, QualType &ReturnType,
+    ExprValueKind &VK) {
+  SourceLocation SelLoc;
+  if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
+    SelLoc = SelectorLocs.front();
+  else
+    SelLoc = lbrac;
+
+  if (!Method) {
+    // Apply default argument promotion as for (C99 6.5.2.2p6).
+    for (unsigned i = 0, e = Args.size(); i != e; i++) {
+      if (Args[i]->isTypeDependent())
+        continue;
+
+      ExprResult result;
+      if (getLangOpts().DebuggerSupport) {
+        QualType paramTy; // ignored
+        result = checkUnknownAnyArg(SelLoc, Args[i], paramTy);
+      } else {
+        result = DefaultArgumentPromotion(Args[i]);
+      }
+      if (result.isInvalid())
+        return true;
+      Args[i] = result.get();
+    }
+
+    unsigned DiagID;
+    if (getLangOpts().ObjCAutoRefCount)
+      DiagID = diag::err_arc_method_not_found;
+    else
+      DiagID = isClassMessage ? diag::warn_class_method_not_found
+                              : diag::warn_inst_method_not_found;
+    if (!getLangOpts().DebuggerSupport) {
+      const ObjCMethodDecl *OMD = SelectorsForTypoCorrection(Sel, ReceiverType);
+      if (OMD && !OMD->isInvalidDecl()) {
+        if (getLangOpts().ObjCAutoRefCount)
+          DiagID = diag::err_method_not_found_with_typo;
+        else
+          DiagID = isClassMessage ? diag::warn_class_method_not_found_with_typo
+                                  : diag::warn_instance_method_not_found_with_typo;
+        Selector MatchedSel = OMD->getSelector();
+        SourceRange SelectorRange(SelectorLocs.front(), SelectorLocs.back());
+        if (MatchedSel.isUnarySelector())
+          Diag(SelLoc, DiagID)
+            << Sel<< isClassMessage << MatchedSel
+            << FixItHint::CreateReplacement(SelectorRange, MatchedSel.getAsString());
+        else
+          Diag(SelLoc, DiagID) << Sel<< isClassMessage << MatchedSel;
+      }
+      else
+        Diag(SelLoc, DiagID)
+          << Sel << isClassMessage << SourceRange(SelectorLocs.front(),
+                                                SelectorLocs.back());
+      // Find the class to which we are sending this message.
+      if (auto *ObjPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
+        if (ObjCInterfaceDecl *ThisClass = ObjPT->getInterfaceDecl()) {
+          Diag(ThisClass->getLocation(), diag::note_receiver_class_declared);
+          if (!RecRange.isInvalid())
+            if (ThisClass->lookupClassMethod(Sel))
+              Diag(RecRange.getBegin(), diag::note_receiver_expr_here)
+                  << FixItHint::CreateReplacement(RecRange,
+                                                  ThisClass->getNameAsString());
+        }
+      }
+    }
+
+    // In debuggers, we want to use __unknown_anytype for these
+    // results so that clients can cast them.
+    if (getLangOpts().DebuggerSupport) {
+      ReturnType = Context.UnknownAnyTy;
+    } else {
+      ReturnType = Context.getObjCIdType();
+    }
+    VK = VK_PRValue;
+    return false;
+  }
+
+  ReturnType = getMessageSendResultType(Receiver, ReceiverType, Method,
+                                        isClassMessage, isSuperMessage);
+  VK = Expr::getValueKindForType(Method->getReturnType());
+
+  unsigned NumNamedArgs = Sel.getNumArgs();
+  // Method might have more arguments than selector indicates. This is due
+  // to addition of c-style arguments in method.
+  if (Method->param_size() > Sel.getNumArgs())
+    NumNamedArgs = Method->param_size();
+  // FIXME. This need be cleaned up.
+  if (Args.size() < NumNamedArgs) {
+    Diag(SelLoc, diag::err_typecheck_call_too_few_args)
+      << 2 << NumNamedArgs << static_cast<unsigned>(Args.size());
+    return false;
+  }
+
+  // Compute the set of type arguments to be substituted into each parameter
+  // type.
+  Optional<ArrayRef<QualType>> typeArgs
+    = ReceiverType->getObjCSubstitutions(Method->getDeclContext());
+  bool IsError = false;
+  for (unsigned i = 0; i < NumNamedArgs; i++) {
+    // We can't do any type-checking on a type-dependent argument.
+    if (Args[i]->isTypeDependent())
+      continue;
+
+    Expr *argExpr = Args[i];
+
+    ParmVarDecl *param = Method->parameters()[i];
+    assert(argExpr && "CheckMessageArgumentTypes(): missing expression");
+
+    if (param->hasAttr<NoEscapeAttr>() &&
+        param->getType()->isBlockPointerType())
+      if (auto *BE = dyn_cast<BlockExpr>(
+              argExpr->IgnoreParenNoopCasts(Context)))
+        BE->getBlockDecl()->setDoesNotEscape();
+
+    // Strip the unbridged-cast placeholder expression off unless it's
+    // a consumed argument.
+    if (argExpr->hasPlaceholderType(BuiltinType::ARCUnbridgedCast) &&
+        !param->hasAttr<CFConsumedAttr>())
+      argExpr = stripARCUnbridgedCast(argExpr);
+
+    // If the parameter is __unknown_anytype, infer its type
+    // from the argument.
+    if (param->getType() == Context.UnknownAnyTy) {
+      QualType paramType;
+      ExprResult argE = checkUnknownAnyArg(SelLoc, argExpr, paramType);
+      if (argE.isInvalid()) {
+        IsError = true;
+      } else {
+        Args[i] = argE.get();
+
+        // Update the parameter type in-place.
+        param->setType(paramType);
+      }
+      continue;
+    }
+
+    QualType origParamType = param->getType();
+    QualType paramType = param->getType();
+    if (typeArgs)
+      paramType = paramType.substObjCTypeArgs(
+                    Context,
+                    *typeArgs,
+                    ObjCSubstitutionContext::Parameter);
+
+    if (RequireCompleteType(argExpr->getSourceRange().getBegin(),
+                            paramType,
+                            diag::err_call_incomplete_argument, argExpr))
+      return true;
+
+    InitializedEntity Entity
+      = InitializedEntity::InitializeParameter(Context, param, paramType);
+    ExprResult ArgE = PerformCopyInitialization(Entity, SourceLocation(), argExpr);
+    if (ArgE.isInvalid())
+      IsError = true;
+    else {
+      Args[i] = ArgE.getAs<Expr>();
+
+      // If we are type-erasing a block to a block-compatible
+      // Objective-C pointer type, we may need to extend the lifetime
+      // of the block object.
+      if (typeArgs && Args[i]->isPRValue() && paramType->isBlockPointerType() &&
+          Args[i]->getType()->isBlockPointerType() &&
+          origParamType->isObjCObjectPointerType()) {
+        ExprResult arg = Args[i];
+        maybeExtendBlockObject(arg);
+        Args[i] = arg.get();
+      }
+    }
+  }
+
+  // Promote additional arguments to variadic methods.
+  if (Method->isVariadic()) {
+    for (unsigned i = NumNamedArgs, e = Args.size(); i < e; ++i) {
+      if (Args[i]->isTypeDependent())
+        continue;
+
+      ExprResult Arg = DefaultVariadicArgumentPromotion(Args[i], VariadicMethod,
+                                                        nullptr);
+      IsError |= Arg.isInvalid();
+      Args[i] = Arg.get();
+    }
+  } else {
+    // Check for extra arguments to non-variadic methods.
+    if (Args.size() != NumNamedArgs) {
+      Diag(Args[NumNamedArgs]->getBeginLoc(),
+           diag::err_typecheck_call_too_many_args)
+          << 2 /*method*/ << NumNamedArgs << static_cast<unsigned>(Args.size())
+          << Method->getSourceRange()
+          << SourceRange(Args[NumNamedArgs]->getBeginLoc(),
+                         Args.back()->getEndLoc());
+    }
+  }
+
+  DiagnoseSentinelCalls(Method, SelLoc, Args);
+
+  // Do additional checkings on method.
+  IsError |= CheckObjCMethodCall(
+      Method, SelLoc, makeArrayRef(Args.data(), Args.size()));
+
+  return IsError;
+}
+
+bool Sema::isSelfExpr(Expr *RExpr) {
+  // 'self' is objc 'self' in an objc method only.
+  ObjCMethodDecl *Method =
+      dyn_cast_or_null<ObjCMethodDecl>(CurContext->getNonClosureAncestor());
+  return isSelfExpr(RExpr, Method);
+}
+
+bool Sema::isSelfExpr(Expr *receiver, const ObjCMethodDecl *method) {
+  if (!method) return false;
+
+  receiver = receiver->IgnoreParenLValueCasts();
+  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(receiver))
+    if (DRE->getDecl() == method->getSelfDecl())
+      return true;
+  return false;
+}
+
+/// LookupMethodInType - Look up a method in an ObjCObjectType.
+ObjCMethodDecl *Sema::LookupMethodInObjectType(Selector sel, QualType type,
+                                               bool isInstance) {
+  const ObjCObjectType *objType = type->castAs<ObjCObjectType>();
+  if (ObjCInterfaceDecl *iface = objType->getInterface()) {
+    // Look it up in the main interface (and categories, etc.)
+    if (ObjCMethodDecl *method = iface->lookupMethod(sel, isInstance))
+      return method;
+
+    // Okay, look for "private" methods declared in any
+    // @implementations we've seen.
+    if (ObjCMethodDecl *method = iface->lookupPrivateMethod(sel, isInstance))
+      return method;
+  }
+
+  // Check qualifiers.
+  for (const auto *I : objType->quals())
+    if (ObjCMethodDecl *method = I->lookupMethod(sel, isInstance))
+      return method;
+
+  return nullptr;
+}
+
+/// LookupMethodInQualifiedType - Lookups up a method in protocol qualifier
+/// list of a qualified objective pointer type.
+ObjCMethodDecl *Sema::LookupMethodInQualifiedType(Selector Sel,
+                                              const ObjCObjectPointerType *OPT,
+                                              bool Instance)
+{
+  ObjCMethodDecl *MD = nullptr;
+  for (const auto *PROTO : OPT->quals()) {
+    if ((MD = PROTO->lookupMethod(Sel, Instance))) {
+      return MD;
+    }
+  }
+  return nullptr;
+}
+
+/// HandleExprPropertyRefExpr - Handle foo.bar where foo is a pointer to an
+/// objective C interface.  This is a property reference expression.
+ExprResult Sema::
+HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
+                          Expr *BaseExpr, SourceLocation OpLoc,
+                          DeclarationName MemberName,
+                          SourceLocation MemberLoc,
+                          SourceLocation SuperLoc, QualType SuperType,
+                          bool Super) {
+  const ObjCInterfaceType *IFaceT = OPT->getInterfaceType();
+  ObjCInterfaceDecl *IFace = IFaceT->getDecl();
+
+  if (!MemberName.isIdentifier()) {
+    Diag(MemberLoc, diag::err_invalid_property_name)
+      << MemberName << QualType(OPT, 0);
+    return ExprError();
+  }
+
+  IdentifierInfo *Member = MemberName.getAsIdentifierInfo();
+
+  SourceRange BaseRange = Super? SourceRange(SuperLoc)
+                               : BaseExpr->getSourceRange();
+  if (RequireCompleteType(MemberLoc, OPT->getPointeeType(),
+                          diag::err_property_not_found_forward_class,
+                          MemberName, BaseRange))
+    return ExprError();
+
+  if (ObjCPropertyDecl *PD = IFace->FindPropertyDeclaration(
+          Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
+    // Check whether we can reference this property.
+    if (DiagnoseUseOfDecl(PD, MemberLoc))
+      return ExprError();
+    if (Super)
+      return new (Context)
+          ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
+                              OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
+    else
+      return new (Context)
+          ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
+                              OK_ObjCProperty, MemberLoc, BaseExpr);
+  }
+  // Check protocols on qualified interfaces.
+  for (const auto *I : OPT->quals())
+    if (ObjCPropertyDecl *PD = I->FindPropertyDeclaration(
+            Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
+      // Check whether we can reference this property.
+      if (DiagnoseUseOfDecl(PD, MemberLoc))
+        return ExprError();
+
+      if (Super)
+        return new (Context) ObjCPropertyRefExpr(
+            PD, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty, MemberLoc,
+            SuperLoc, SuperType);
+      else
+        return new (Context)
+            ObjCPropertyRefExpr(PD, Context.PseudoObjectTy, VK_LValue,
+                                OK_ObjCProperty, MemberLoc, BaseExpr);
+    }
+  // If that failed, look for an "implicit" property by seeing if the nullary
+  // selector is implemented.
+
+  // FIXME: The logic for looking up nullary and unary selectors should be
+  // shared with the code in ActOnInstanceMessage.
+
+  Selector Sel = PP.getSelectorTable().getNullarySelector(Member);
+  ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Sel);
+
+  // May be found in property's qualified list.
+  if (!Getter)
+    Getter = LookupMethodInQualifiedType(Sel, OPT, true);
+
+  // If this reference is in an @implementation, check for 'private' methods.
+  if (!Getter)
+    Getter = IFace->lookupPrivateMethod(Sel);
+
+  if (Getter) {
+    // Check if we can reference this property.
+    if (DiagnoseUseOfDecl(Getter, MemberLoc))
+      return ExprError();
+  }
+  // If we found a getter then this may be a valid dot-reference, we
+  // will look for the matching setter, in case it is needed.
+  Selector SetterSel =
+    SelectorTable::constructSetterSelector(PP.getIdentifierTable(),
+                                           PP.getSelectorTable(), Member);
+  ObjCMethodDecl *Setter = IFace->lookupInstanceMethod(SetterSel);
+
+  // May be found in property's qualified list.
+  if (!Setter)
+    Setter = LookupMethodInQualifiedType(SetterSel, OPT, true);
+
+  if (!Setter) {
+    // If this reference is in an @implementation, also check for 'private'
+    // methods.
+    Setter = IFace->lookupPrivateMethod(SetterSel);
+  }
+
+  if (Setter && DiagnoseUseOfDecl(Setter, MemberLoc))
+    return ExprError();
+
+  // Special warning if member name used in a property-dot for a setter accessor
+  // does not use a property with same name; e.g. obj.X = ... for a property with
+  // name 'x'.
+  if (Setter && Setter->isImplicit() && Setter->isPropertyAccessor() &&
+      !IFace->FindPropertyDeclaration(
+          Member, ObjCPropertyQueryKind::OBJC_PR_query_instance)) {
+      if (const ObjCPropertyDecl *PDecl = Setter->findPropertyDecl()) {
+        // Do not warn if user is using property-dot syntax to make call to
+        // user named setter.
+        if (!(PDecl->getPropertyAttributes() &
+              ObjCPropertyAttribute::kind_setter))
+          Diag(MemberLoc,
+               diag::warn_property_access_suggest)
+          << MemberName << QualType(OPT, 0) << PDecl->getName()
+          << FixItHint::CreateReplacement(MemberLoc, PDecl->getName());
+      }
+  }
+
+  if (Getter || Setter) {
+    if (Super)
+      return new (Context)
+          ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
+                              OK_ObjCProperty, MemberLoc, SuperLoc, SuperType);
+    else
+      return new (Context)
+          ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
+                              OK_ObjCProperty, MemberLoc, BaseExpr);
+
+  }
+
+  // Attempt to correct for typos in property names.
+  DeclFilterCCC<ObjCPropertyDecl> CCC{};
+  if (TypoCorrection Corrected = CorrectTypo(
+          DeclarationNameInfo(MemberName, MemberLoc), LookupOrdinaryName,
+          nullptr, nullptr, CCC, CTK_ErrorRecovery, IFace, false, OPT)) {
+    DeclarationName TypoResult = Corrected.getCorrection();
+    if (TypoResult.isIdentifier() &&
+        TypoResult.getAsIdentifierInfo() == Member) {
+      // There is no need to try the correction if it is the same.
+      NamedDecl *ChosenDecl =
+        Corrected.isKeyword() ? nullptr : Corrected.getFoundDecl();
+      if (ChosenDecl && isa<ObjCPropertyDecl>(ChosenDecl))
+        if (cast<ObjCPropertyDecl>(ChosenDecl)->isClassProperty()) {
+          // This is a class property, we should not use the instance to
+          // access it.
+          Diag(MemberLoc, diag::err_class_property_found) << MemberName
+          << OPT->getInterfaceDecl()->getName()
+          << FixItHint::CreateReplacement(BaseExpr->getSourceRange(),
+                                          OPT->getInterfaceDecl()->getName());
+          return ExprError();
+        }
+    } else {
+      diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
+                                << MemberName << QualType(OPT, 0));
+      return HandleExprPropertyRefExpr(OPT, BaseExpr, OpLoc,
+                                       TypoResult, MemberLoc,
+                                       SuperLoc, SuperType, Super);
+    }
+  }
+  ObjCInterfaceDecl *ClassDeclared;
+  if (ObjCIvarDecl *Ivar =
+      IFace->lookupInstanceVariable(Member, ClassDeclared)) {
+    QualType T = Ivar->getType();
+    if (const ObjCObjectPointerType * OBJPT =
+        T->getAsObjCInterfacePointerType()) {
+      if (RequireCompleteType(MemberLoc, OBJPT->getPointeeType(),
+                              diag::err_property_not_as_forward_class,
+                              MemberName, BaseExpr))
+        return ExprError();
+    }
+    Diag(MemberLoc,
+         diag::err_ivar_access_using_property_syntax_suggest)
+    << MemberName << QualType(OPT, 0) << Ivar->getDeclName()
+    << FixItHint::CreateReplacement(OpLoc, "->");
+    return ExprError();
+  }
+
+  Diag(MemberLoc, diag::err_property_not_found)
+    << MemberName << QualType(OPT, 0);
+  if (Setter)
+    Diag(Setter->getLocation(), diag::note_getter_unavailable)
+          << MemberName << BaseExpr->getSourceRange();
+  return ExprError();
+}
+
+ExprResult Sema::
+ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
+                          IdentifierInfo &propertyName,
+                          SourceLocation receiverNameLoc,
+                          SourceLocation propertyNameLoc) {
+
+  IdentifierInfo *receiverNamePtr = &receiverName;
+  ObjCInterfaceDecl *IFace = getObjCInterfaceDecl(receiverNamePtr,
+                                                  receiverNameLoc);
+
+  QualType SuperType;
+  if (!IFace) {
+    // If the "receiver" is 'super' in a method, handle it as an expression-like
+    // property reference.
+    if (receiverNamePtr->isStr("super")) {
+      if (ObjCMethodDecl *CurMethod = tryCaptureObjCSelf(receiverNameLoc)) {
+        if (auto classDecl = CurMethod->getClassInterface()) {
+          SuperType = QualType(classDecl->getSuperClassType(), 0);
+          if (CurMethod->isInstanceMethod()) {
+            if (SuperType.isNull()) {
+              // The current class does not have a superclass.
+              Diag(receiverNameLoc, diag::err_root_class_cannot_use_super)
+                << CurMethod->getClassInterface()->getIdentifier();
+              return ExprError();
+            }
+            QualType T = Context.getObjCObjectPointerType(SuperType);
+
+            return HandleExprPropertyRefExpr(T->castAs<ObjCObjectPointerType>(),
+                                             /*BaseExpr*/nullptr,
+                                             SourceLocation()/*OpLoc*/,
+                                             &propertyName,
+                                             propertyNameLoc,
+                                             receiverNameLoc, T, true);
+          }
+
+          // Otherwise, if this is a class method, try dispatching to our
+          // superclass.
+          IFace = CurMethod->getClassInterface()->getSuperClass();
+        }
+      }
+    }
+
+    if (!IFace) {
+      Diag(receiverNameLoc, diag::err_expected_either) << tok::identifier
+                                                       << tok::l_paren;
+      return ExprError();
+    }
+  }
+
+  Selector GetterSel;
+  Selector SetterSel;
+  if (auto PD = IFace->FindPropertyDeclaration(
+          &propertyName, ObjCPropertyQueryKind::OBJC_PR_query_class)) {
+    GetterSel = PD->getGetterName();
+    SetterSel = PD->getSetterName();
+  } else {
+    GetterSel = PP.getSelectorTable().getNullarySelector(&propertyName);
+    SetterSel = SelectorTable::constructSetterSelector(
+        PP.getIdentifierTable(), PP.getSelectorTable(), &propertyName);
+  }
+
+  // Search for a declared property first.
+  ObjCMethodDecl *Getter = IFace->lookupClassMethod(GetterSel);
+
+  // If this reference is in an @implementation, check for 'private' methods.
+  if (!Getter)
+    Getter = IFace->lookupPrivateClassMethod(GetterSel);
+
+  if (Getter) {
+    // FIXME: refactor/share with ActOnMemberReference().
+    // Check if we can reference this property.
+    if (DiagnoseUseOfDecl(Getter, propertyNameLoc))
+      return ExprError();
+  }
+
+  // Look for the matching setter, in case it is needed.
+  ObjCMethodDecl *Setter = IFace->lookupClassMethod(SetterSel);
+  if (!Setter) {
+    // If this reference is in an @implementation, also check for 'private'
+    // methods.
+    Setter = IFace->lookupPrivateClassMethod(SetterSel);
+  }
+  // Look through local category implementations associated with the class.
+  if (!Setter)
+    Setter = IFace->getCategoryClassMethod(SetterSel);
+
+  if (Setter && DiagnoseUseOfDecl(Setter, propertyNameLoc))
+    return ExprError();
+
+  if (Getter || Setter) {
+    if (!SuperType.isNull())
+      return new (Context)
+          ObjCPropertyRefExpr(Getter, Setter, Context.PseudoObjectTy, VK_LValue,
+                              OK_ObjCProperty, propertyNameLoc, receiverNameLoc,
+                              SuperType);
+
+    return new (Context) ObjCPropertyRefExpr(
+        Getter, Setter, Context.PseudoObjectTy, VK_LValue, OK_ObjCProperty,
+        propertyNameLoc, receiverNameLoc, IFace);
+  }
+  return ExprError(Diag(propertyNameLoc, diag::err_property_not_found)
+                     << &propertyName << Context.getObjCInterfaceType(IFace));
+}
+
+namespace {
+
+class ObjCInterfaceOrSuperCCC final : public CorrectionCandidateCallback {
+ public:
+  ObjCInterfaceOrSuperCCC(ObjCMethodDecl *Method) {
+    // Determine whether "super" is acceptable in the current context.
+    if (Method && Method->getClassInterface())
+      WantObjCSuper = Method->getClassInterface()->getSuperClass();
+  }
+
+  bool ValidateCandidate(const TypoCorrection &candidate) override {
+    return candidate.getCorrectionDeclAs<ObjCInterfaceDecl>() ||
+        candidate.isKeyword("super");
+  }
+
+  std::unique_ptr<CorrectionCandidateCallback> clone() override {
+    return std::make_unique<ObjCInterfaceOrSuperCCC>(*this);
+  }
+};
+
+} // end anonymous namespace
+
+Sema::ObjCMessageKind Sema::getObjCMessageKind(Scope *S,
+                                               IdentifierInfo *Name,
+                                               SourceLocation NameLoc,
+                                               bool IsSuper,
+                                               bool HasTrailingDot,
+                                               ParsedType &ReceiverType) {
+  ReceiverType = nullptr;
+
+  // If the identifier is "super" and there is no trailing dot, we're
+  // messaging super. If the identifier is "super" and there is a
+  // trailing dot, it's an instance message.
+  if (IsSuper && S->isInObjcMethodScope())
+    return HasTrailingDot? ObjCInstanceMessage : ObjCSuperMessage;
+
+  LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
+  LookupName(Result, S);
+
+  switch (Result.getResultKind()) {
+  case LookupResult::NotFound:
+    // Normal name lookup didn't find anything. If we're in an
+    // Objective-C method, look for ivars. If we find one, we're done!
+    // FIXME: This is a hack. Ivar lookup should be part of normal
+    // lookup.
+    if (ObjCMethodDecl *Method = getCurMethodDecl()) {
+      if (!Method->getClassInterface()) {
+        // Fall back: let the parser try to parse it as an instance message.
+        return ObjCInstanceMessage;
+      }
+
+      ObjCInterfaceDecl *ClassDeclared;
+      if (Method->getClassInterface()->lookupInstanceVariable(Name,
+                                                              ClassDeclared))
+        return ObjCInstanceMessage;
+    }
+
+    // Break out; we'll perform typo correction below.
+    break;
+
+  case LookupResult::NotFoundInCurrentInstantiation:
+  case LookupResult::FoundOverloaded:
+  case LookupResult::FoundUnresolvedValue:
+  case LookupResult::Ambiguous:
+    Result.suppressDiagnostics();
+    return ObjCInstanceMessage;
+
+  case LookupResult::Found: {
+    // If the identifier is a class or not, and there is a trailing dot,
+    // it's an instance message.
+    if (HasTrailingDot)
+      return ObjCInstanceMessage;
+    // We found something. If it's a type, then we have a class
+    // message. Otherwise, it's an instance message.
+    NamedDecl *ND = Result.getFoundDecl();
+    QualType T;
+    if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(ND))
+      T = Context.getObjCInterfaceType(Class);
+    else if (TypeDecl *Type = dyn_cast<TypeDecl>(ND)) {
+      T = Context.getTypeDeclType(Type);
+      DiagnoseUseOfDecl(Type, NameLoc);
+    }
+    else
+      return ObjCInstanceMessage;
+
+    //  We have a class message, and T is the type we're
+    //  messaging. Build source-location information for it.
+    TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
+    ReceiverType = CreateParsedType(T, TSInfo);
+    return ObjCClassMessage;
+  }
+  }
+
+  ObjCInterfaceOrSuperCCC CCC(getCurMethodDecl());
+  if (TypoCorrection Corrected = CorrectTypo(
+          Result.getLookupNameInfo(), Result.getLookupKind(), S, nullptr, CCC,
+          CTK_ErrorRecovery, nullptr, false, nullptr, false)) {
+    if (Corrected.isKeyword()) {
+      // If we've found the keyword "super" (the only keyword that would be
+      // returned by CorrectTypo), this is a send to super.
+      diagnoseTypo(Corrected,
+                   PDiag(diag::err_unknown_receiver_suggest) << Name);
+      return ObjCSuperMessage;
+    } else if (ObjCInterfaceDecl *Class =
+                   Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
+      // If we found a declaration, correct when it refers to an Objective-C
+      // class.
+      diagnoseTypo(Corrected,
+                   PDiag(diag::err_unknown_receiver_suggest) << Name);
+      QualType T = Context.getObjCInterfaceType(Class);
+      TypeSourceInfo *TSInfo = Context.getTrivialTypeSourceInfo(T, NameLoc);
+      ReceiverType = CreateParsedType(T, TSInfo);
+      return ObjCClassMessage;
+    }
+  }
+
+  // Fall back: let the parser try to parse it as an instance message.
+  return ObjCInstanceMessage;
+}
+
+ExprResult Sema::ActOnSuperMessage(Scope *S,
+                                   SourceLocation SuperLoc,
+                                   Selector Sel,
+                                   SourceLocation LBracLoc,
+                                   ArrayRef<SourceLocation> SelectorLocs,
+                                   SourceLocation RBracLoc,
+                                   MultiExprArg Args) {
+  // Determine whether we are inside a method or not.
+  ObjCMethodDecl *Method = tryCaptureObjCSelf(SuperLoc);
+  if (!Method) {
+    Diag(SuperLoc, diag::err_invalid_receiver_to_message_super);
+    return ExprError();
+  }
+
+  ObjCInterfaceDecl *Class = Method->getClassInterface();
+  if (!Class) {
+    Diag(SuperLoc, diag::err_no_super_class_message)
+      << Method->getDeclName();
+    return ExprError();
+  }
+
+  QualType SuperTy(Class->getSuperClassType(), 0);
+  if (SuperTy.isNull()) {
+    // The current class does not have a superclass.
+    Diag(SuperLoc, diag::err_root_class_cannot_use_super)
+      << Class->getIdentifier();
+    return ExprError();
+  }
+
+  // We are in a method whose class has a superclass, so 'super'
+  // is acting as a keyword.
+  if (Method->getSelector() == Sel)
+    getCurFunction()->ObjCShouldCallSuper = false;
+
+  if (Method->isInstanceMethod()) {
+    // Since we are in an instance method, this is an instance
+    // message to the superclass instance.
+    SuperTy = Context.getObjCObjectPointerType(SuperTy);
+    return BuildInstanceMessage(nullptr, SuperTy, SuperLoc,
+                                Sel, /*Method=*/nullptr,
+                                LBracLoc, SelectorLocs, RBracLoc, Args);
+  }
+
+  // Since we are in a class method, this is a class message to
+  // the superclass.
+  return BuildClassMessage(/*ReceiverTypeInfo=*/nullptr,
+                           SuperTy,
+                           SuperLoc, Sel, /*Method=*/nullptr,
+                           LBracLoc, SelectorLocs, RBracLoc, Args);
+}
+
+ExprResult Sema::BuildClassMessageImplicit(QualType ReceiverType,
+                                           bool isSuperReceiver,
+                                           SourceLocation Loc,
+                                           Selector Sel,
+                                           ObjCMethodDecl *Method,
+                                           MultiExprArg Args) {
+  TypeSourceInfo *receiverTypeInfo = nullptr;
+  if (!ReceiverType.isNull())
+    receiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType);
+
+  return BuildClassMessage(receiverTypeInfo, ReceiverType,
+                          /*SuperLoc=*/isSuperReceiver ? Loc : SourceLocation(),
+                           Sel, Method, Loc, Loc, Loc, Args,
+                           /*isImplicit=*/true);
+}
+
+static void applyCocoaAPICheck(Sema &S, const ObjCMessageExpr *Msg,
+                               unsigned DiagID,
+                               bool (*refactor)(const ObjCMessageExpr *,
+                                              const NSAPI &, edit::Commit &)) {
+  SourceLocation MsgLoc = Msg->getExprLoc();
+  if (S.Diags.isIgnored(DiagID, MsgLoc))
+    return;
+
+  SourceManager &SM = S.SourceMgr;
+  edit::Commit ECommit(SM, S.LangOpts);
+  if (refactor(Msg,*S.NSAPIObj, ECommit)) {
+    auto Builder = S.Diag(MsgLoc, DiagID)
+                   << Msg->getSelector() << Msg->getSourceRange();
+    // FIXME: Don't emit diagnostic at all if fixits are non-commitable.
+    if (!ECommit.isCommitable())
+      return;
+    for (edit::Commit::edit_iterator
+           I = ECommit.edit_begin(), E = ECommit.edit_end(); I != E; ++I) {
+      const edit::Commit::Edit &Edit = *I;
+      switch (Edit.Kind) {
+      case edit::Commit::Act_Insert:
+        Builder.AddFixItHint(FixItHint::CreateInsertion(Edit.OrigLoc,
+                                                        Edit.Text,
+                                                        Edit.BeforePrev));
+        break;
+      case edit::Commit::Act_InsertFromRange:
+        Builder.AddFixItHint(
+            FixItHint::CreateInsertionFromRange(Edit.OrigLoc,
+                                                Edit.getInsertFromRange(SM),
+                                                Edit.BeforePrev));
+        break;
+      case edit::Commit::Act_Remove:
+        Builder.AddFixItHint(FixItHint::CreateRemoval(Edit.getFileRange(SM)));
+        break;
+      }
+    }
+  }
+}
+
+static void checkCocoaAPI(Sema &S, const ObjCMessageExpr *Msg) {
+  applyCocoaAPICheck(S, Msg, diag::warn_objc_redundant_literal_use,
+                     edit::rewriteObjCRedundantCallWithLiteral);
+}
+
+static void checkFoundationAPI(Sema &S, SourceLocation Loc,
+                               const ObjCMethodDecl *Method,
+                               ArrayRef<Expr *> Args, QualType ReceiverType,
+                               bool IsClassObjectCall) {
+  // Check if this is a performSelector method that uses a selector that returns
+  // a record or a vector type.
+  if (Method->getSelector().getMethodFamily() != OMF_performSelector ||
+      Args.empty())
+    return;
+  const auto *SE = dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens());
+  if (!SE)
+    return;
+  ObjCMethodDecl *ImpliedMethod;
+  if (!IsClassObjectCall) {
+    const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>();
+    if (!OPT || !OPT->getInterfaceDecl())
+      return;
+    ImpliedMethod =
+        OPT->getInterfaceDecl()->lookupInstanceMethod(SE->getSelector());
+    if (!ImpliedMethod)
+      ImpliedMethod =
+          OPT->getInterfaceDecl()->lookupPrivateMethod(SE->getSelector());
+  } else {
+    const auto *IT = ReceiverType->getAs<ObjCInterfaceType>();
+    if (!IT)
+      return;
+    ImpliedMethod = IT->getDecl()->lookupClassMethod(SE->getSelector());
+    if (!ImpliedMethod)
+      ImpliedMethod =
+          IT->getDecl()->lookupPrivateClassMethod(SE->getSelector());
+  }
+  if (!ImpliedMethod)
+    return;
+  QualType Ret = ImpliedMethod->getReturnType();
+  if (Ret->isRecordType() || Ret->isVectorType() || Ret->isExtVectorType()) {
+    S.Diag(Loc, diag::warn_objc_unsafe_perform_selector)
+        << Method->getSelector()
+        << (!Ret->isRecordType()
+                ? /*Vector*/ 2
+                : Ret->isUnionType() ? /*Union*/ 1 : /*Struct*/ 0);
+    S.Diag(ImpliedMethod->getBeginLoc(),
+           diag::note_objc_unsafe_perform_selector_method_declared_here)
+        << ImpliedMethod->getSelector() << Ret;
+  }
+}
+
+/// Diagnose use of %s directive in an NSString which is being passed
+/// as formatting string to formatting method.
+static void
+DiagnoseCStringFormatDirectiveInObjCAPI(Sema &S,
+                                        ObjCMethodDecl *Method,
+                                        Selector Sel,
+                                        Expr **Args, unsigned NumArgs) {
+  unsigned Idx = 0;
+  bool Format = false;
+  ObjCStringFormatFamily SFFamily = Sel.getStringFormatFamily();
+  if (SFFamily == ObjCStringFormatFamily::SFF_NSString) {
+    Idx = 0;
+    Format = true;
+  }
+  else if (Method) {
+    for (const auto *I : Method->specific_attrs<FormatAttr>()) {
+      if (S.GetFormatNSStringIdx(I, Idx)) {
+        Format = true;
+        break;
+      }
+    }
+  }
+  if (!Format || NumArgs <= Idx)
+    return;
+
+  Expr *FormatExpr = Args[Idx];
+  if (ObjCStringLiteral *OSL =
+      dyn_cast<ObjCStringLiteral>(FormatExpr->IgnoreParenImpCasts())) {
+    StringLiteral *FormatString = OSL->getString();
+    if (S.FormatStringHasSArg(FormatString)) {
+      S.Diag(FormatExpr->getExprLoc(), diag::warn_objc_cdirective_format_string)
+        << "%s" << 0 << 0;
+      if (Method)
+        S.Diag(Method->getLocation(), diag::note_method_declared_at)
+          << Method->getDeclName();
+    }
+  }
+}
+
+/// Build an Objective-C class message expression.
+///
+/// This routine takes care of both normal class messages and
+/// class messages to the superclass.
+///
+/// \param ReceiverTypeInfo Type source information that describes the
+/// receiver of this message. This may be NULL, in which case we are
+/// sending to the superclass and \p SuperLoc must be a valid source
+/// location.
+
+/// \param ReceiverType The type of the object receiving the
+/// message. When \p ReceiverTypeInfo is non-NULL, this is the same
+/// type as that refers to. For a superclass send, this is the type of
+/// the superclass.
+///
+/// \param SuperLoc The location of the "super" keyword in a
+/// superclass message.
+///
+/// \param Sel The selector to which the message is being sent.
+///
+/// \param Method The method that this class message is invoking, if
+/// already known.
+///
+/// \param LBracLoc The location of the opening square bracket ']'.
+///
+/// \param RBracLoc The location of the closing square bracket ']'.
+///
+/// \param ArgsIn The message arguments.
+ExprResult Sema::BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
+                                   QualType ReceiverType,
+                                   SourceLocation SuperLoc,
+                                   Selector Sel,
+                                   ObjCMethodDecl *Method,
+                                   SourceLocation LBracLoc,
+                                   ArrayRef<SourceLocation> SelectorLocs,
+                                   SourceLocation RBracLoc,
+                                   MultiExprArg ArgsIn,
+                                   bool isImplicit) {
+  SourceLocation Loc = SuperLoc.isValid()? SuperLoc
+    : ReceiverTypeInfo->getTypeLoc().getSourceRange().getBegin();
+  if (LBracLoc.isInvalid()) {
+    Diag(Loc, diag::err_missing_open_square_message_send)
+      << FixItHint::CreateInsertion(Loc, "[");
+    LBracLoc = Loc;
+  }
+  ArrayRef<SourceLocation> SelectorSlotLocs;
+  if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
+    SelectorSlotLocs = SelectorLocs;
+  else
+    SelectorSlotLocs = Loc;
+  SourceLocation SelLoc = SelectorSlotLocs.front();
+
+  if (ReceiverType->isDependentType()) {
+    // If the receiver type is dependent, we can't type-check anything
+    // at this point. Build a dependent expression.
+    unsigned NumArgs = ArgsIn.size();
+    Expr **Args = ArgsIn.data();
+    assert(SuperLoc.isInvalid() && "Message to super with dependent type");
+    return ObjCMessageExpr::Create(
+        Context, ReceiverType, VK_PRValue, LBracLoc, ReceiverTypeInfo, Sel,
+        SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs), RBracLoc,
+        isImplicit);
+  }
+
+  // Find the class to which we are sending this message.
+  ObjCInterfaceDecl *Class = nullptr;
+  const ObjCObjectType *ClassType = ReceiverType->getAs<ObjCObjectType>();
+  if (!ClassType || !(Class = ClassType->getInterface())) {
+    Diag(Loc, diag::err_invalid_receiver_class_message)
+      << ReceiverType;
+    return ExprError();
+  }
+  assert(Class && "We don't know which class we're messaging?");
+  // objc++ diagnoses during typename annotation.
+  if (!getLangOpts().CPlusPlus)
+    (void)DiagnoseUseOfDecl(Class, SelectorSlotLocs);
+  // Find the method we are messaging.
+  if (!Method) {
+    SourceRange TypeRange
+      = SuperLoc.isValid()? SourceRange(SuperLoc)
+                          : ReceiverTypeInfo->getTypeLoc().getSourceRange();
+    if (RequireCompleteType(Loc, Context.getObjCInterfaceType(Class),
+                            (getLangOpts().ObjCAutoRefCount
+                               ? diag::err_arc_receiver_forward_class
+                               : diag::warn_receiver_forward_class),
+                            TypeRange)) {
+      // A forward class used in messaging is treated as a 'Class'
+      Method = LookupFactoryMethodInGlobalPool(Sel,
+                                               SourceRange(LBracLoc, RBracLoc));
+      if (Method && !getLangOpts().ObjCAutoRefCount)
+        Diag(Method->getLocation(), diag::note_method_sent_forward_class)
+          << Method->getDeclName();
+    }
+    if (!Method)
+      Method = Class->lookupClassMethod(Sel);
+
+    // If we have an implementation in scope, check "private" methods.
+    if (!Method)
+      Method = Class->lookupPrivateClassMethod(Sel);
+
+    if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs,
+                                    nullptr, false, false, Class))
+      return ExprError();
+  }
+
+  // Check the argument types and determine the result type.
+  QualType ReturnType;
+  ExprValueKind VK = VK_PRValue;
+
+  unsigned NumArgs = ArgsIn.size();
+  Expr **Args = ArgsIn.data();
+  if (CheckMessageArgumentTypes(/*Receiver=*/nullptr, ReceiverType,
+                                MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
+                                Method, true, SuperLoc.isValid(), LBracLoc,
+                                RBracLoc, SourceRange(), ReturnType, VK))
+    return ExprError();
+
+  if (Method && !Method->getReturnType()->isVoidType() &&
+      RequireCompleteType(LBracLoc, Method->getReturnType(),
+                          diag::err_illegal_message_expr_incomplete_type))
+    return ExprError();
+
+  if (Method && Method->isDirectMethod() && SuperLoc.isValid()) {
+    Diag(SuperLoc, diag::err_messaging_super_with_direct_method)
+        << FixItHint::CreateReplacement(
+               SuperLoc, getLangOpts().ObjCAutoRefCount
+                             ? "self"
+                             : Method->getClassInterface()->getName());
+    Diag(Method->getLocation(), diag::note_direct_method_declared_at)
+        << Method->getDeclName();
+  }
+
+  // Warn about explicit call of +initialize on its own class. But not on 'super'.
+  if (Method && Method->getMethodFamily() == OMF_initialize) {
+    if (!SuperLoc.isValid()) {
+      const ObjCInterfaceDecl *ID =
+        dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext());
+      if (ID == Class) {
+        Diag(Loc, diag::warn_direct_initialize_call);
+        Diag(Method->getLocation(), diag::note_method_declared_at)
+          << Method->getDeclName();
+      }
+    }
+    else if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
+      // [super initialize] is allowed only within an +initialize implementation
+      if (CurMeth->getMethodFamily() != OMF_initialize) {
+        Diag(Loc, diag::warn_direct_super_initialize_call);
+        Diag(Method->getLocation(), diag::note_method_declared_at)
+          << Method->getDeclName();
+        Diag(CurMeth->getLocation(), diag::note_method_declared_at)
+        << CurMeth->getDeclName();
+      }
+    }
+  }
+
+  DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
+
+  // Construct the appropriate ObjCMessageExpr.
+  ObjCMessageExpr *Result;
+  if (SuperLoc.isValid())
+    Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
+                                     SuperLoc, /*IsInstanceSuper=*/false,
+                                     ReceiverType, Sel, SelectorLocs,
+                                     Method, makeArrayRef(Args, NumArgs),
+                                     RBracLoc, isImplicit);
+  else {
+    Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
+                                     ReceiverTypeInfo, Sel, SelectorLocs,
+                                     Method, makeArrayRef(Args, NumArgs),
+                                     RBracLoc, isImplicit);
+    if (!isImplicit)
+      checkCocoaAPI(*this, Result);
+  }
+  if (Method)
+    checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
+                       ReceiverType, /*IsClassObjectCall=*/true);
+  return MaybeBindToTemporary(Result);
+}
+
+// ActOnClassMessage - used for both unary and keyword messages.
+// ArgExprs is optional - if it is present, the number of expressions
+// is obtained from Sel.getNumArgs().
+ExprResult Sema::ActOnClassMessage(Scope *S,
+                                   ParsedType Receiver,
+                                   Selector Sel,
+                                   SourceLocation LBracLoc,
+                                   ArrayRef<SourceLocation> SelectorLocs,
+                                   SourceLocation RBracLoc,
+                                   MultiExprArg Args) {
+  TypeSourceInfo *ReceiverTypeInfo;
+  QualType ReceiverType = GetTypeFromParser(Receiver, &ReceiverTypeInfo);
+  if (ReceiverType.isNull())
+    return ExprError();
+
+  if (!ReceiverTypeInfo)
+    ReceiverTypeInfo = Context.getTrivialTypeSourceInfo(ReceiverType, LBracLoc);
+
+  return BuildClassMessage(ReceiverTypeInfo, ReceiverType,
+                           /*SuperLoc=*/SourceLocation(), Sel,
+                           /*Method=*/nullptr, LBracLoc, SelectorLocs, RBracLoc,
+                           Args);
+}
+
+ExprResult Sema::BuildInstanceMessageImplicit(Expr *Receiver,
+                                              QualType ReceiverType,
+                                              SourceLocation Loc,
+                                              Selector Sel,
+                                              ObjCMethodDecl *Method,
+                                              MultiExprArg Args) {
+  return BuildInstanceMessage(Receiver, ReceiverType,
+                              /*SuperLoc=*/!Receiver ? Loc : SourceLocation(),
+                              Sel, Method, Loc, Loc, Loc, Args,
+                              /*isImplicit=*/true);
+}
+
+static bool isMethodDeclaredInRootProtocol(Sema &S, const ObjCMethodDecl *M) {
+  if (!S.NSAPIObj)
+    return false;
+  const auto *Protocol = dyn_cast<ObjCProtocolDecl>(M->getDeclContext());
+  if (!Protocol)
+    return false;
+  const IdentifierInfo *II = S.NSAPIObj->getNSClassId(NSAPI::ClassId_NSObject);
+  if (const auto *RootClass = dyn_cast_or_null<ObjCInterfaceDecl>(
+          S.LookupSingleName(S.TUScope, II, Protocol->getBeginLoc(),
+                             Sema::LookupOrdinaryName))) {
+    for (const ObjCProtocolDecl *P : RootClass->all_referenced_protocols()) {
+      if (P->getCanonicalDecl() == Protocol->getCanonicalDecl())
+        return true;
+    }
+  }
+  return false;
+}
+
+/// Build an Objective-C instance message expression.
+///
+/// This routine takes care of both normal instance messages and
+/// instance messages to the superclass instance.
+///
+/// \param Receiver The expression that computes the object that will
+/// receive this message. This may be empty, in which case we are
+/// sending to the superclass instance and \p SuperLoc must be a valid
+/// source location.
+///
+/// \param ReceiverType The (static) type of the object receiving the
+/// message. When a \p Receiver expression is provided, this is the
+/// same type as that expression. For a superclass instance send, this
+/// is a pointer to the type of the superclass.
+///
+/// \param SuperLoc The location of the "super" keyword in a
+/// superclass instance message.
+///
+/// \param Sel The selector to which the message is being sent.
+///
+/// \param Method The method that this instance message is invoking, if
+/// already known.
+///
+/// \param LBracLoc The location of the opening square bracket ']'.
+///
+/// \param RBracLoc The location of the closing square bracket ']'.
+///
+/// \param ArgsIn The message arguments.
+ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
+                                      QualType ReceiverType,
+                                      SourceLocation SuperLoc,
+                                      Selector Sel,
+                                      ObjCMethodDecl *Method,
+                                      SourceLocation LBracLoc,
+                                      ArrayRef<SourceLocation> SelectorLocs,
+                                      SourceLocation RBracLoc,
+                                      MultiExprArg ArgsIn,
+                                      bool isImplicit) {
+  assert((Receiver || SuperLoc.isValid()) && "If the Receiver is null, the "
+                                             "SuperLoc must be valid so we can "
+                                             "use it instead.");
+
+  // The location of the receiver.
+  SourceLocation Loc = SuperLoc.isValid() ? SuperLoc : Receiver->getBeginLoc();
+  SourceRange RecRange =
+      SuperLoc.isValid()? SuperLoc : Receiver->getSourceRange();
+  ArrayRef<SourceLocation> SelectorSlotLocs;
+  if (!SelectorLocs.empty() && SelectorLocs.front().isValid())
+    SelectorSlotLocs = SelectorLocs;
+  else
+    SelectorSlotLocs = Loc;
+  SourceLocation SelLoc = SelectorSlotLocs.front();
+
+  if (LBracLoc.isInvalid()) {
+    Diag(Loc, diag::err_missing_open_square_message_send)
+      << FixItHint::CreateInsertion(Loc, "[");
+    LBracLoc = Loc;
+  }
+
+  // If we have a receiver expression, perform appropriate promotions
+  // and determine receiver type.
+  if (Receiver) {
+    if (Receiver->hasPlaceholderType()) {
+      ExprResult Result;
+      if (Receiver->getType() == Context.UnknownAnyTy)
+        Result = forceUnknownAnyToType(Receiver, Context.getObjCIdType());
+      else
+        Result = CheckPlaceholderExpr(Receiver);
+      if (Result.isInvalid()) return ExprError();
+      Receiver = Result.get();
+    }
+
+    if (Receiver->isTypeDependent()) {
+      // If the receiver is type-dependent, we can't type-check anything
+      // at this point. Build a dependent expression.
+      unsigned NumArgs = ArgsIn.size();
+      Expr **Args = ArgsIn.data();
+      assert(SuperLoc.isInvalid() && "Message to super with dependent type");
+      return ObjCMessageExpr::Create(
+          Context, Context.DependentTy, VK_PRValue, LBracLoc, Receiver, Sel,
+          SelectorLocs, /*Method=*/nullptr, makeArrayRef(Args, NumArgs),
+          RBracLoc, isImplicit);
+    }
+
+    // If necessary, apply function/array conversion to the receiver.
+    // C99 6.7.5.3p[7,8].
+    ExprResult Result = DefaultFunctionArrayLvalueConversion(Receiver);
+    if (Result.isInvalid())
+      return ExprError();
+    Receiver = Result.get();
+    ReceiverType = Receiver->getType();
+
+    // If the receiver is an ObjC pointer, a block pointer, or an
+    // __attribute__((NSObject)) pointer, we don't need to do any
+    // special conversion in order to look up a receiver.
+    if (ReceiverType->isObjCRetainableType()) {
+      // do nothing
+    } else if (!getLangOpts().ObjCAutoRefCount &&
+               !Context.getObjCIdType().isNull() &&
+               (ReceiverType->isPointerType() ||
+                ReceiverType->isIntegerType())) {
+      // Implicitly convert integers and pointers to 'id' but emit a warning.
+      // But not in ARC.
+      Diag(Loc, diag::warn_bad_receiver_type) << ReceiverType << RecRange;
+      if (ReceiverType->isPointerType()) {
+        Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
+                                     CK_CPointerToObjCPointerCast).get();
+      } else {
+        // TODO: specialized warning on null receivers?
+        bool IsNull = Receiver->isNullPointerConstant(Context,
+                                              Expr::NPC_ValueDependentIsNull);
+        CastKind Kind = IsNull ? CK_NullToPointer : CK_IntegralToPointer;
+        Receiver = ImpCastExprToType(Receiver, Context.getObjCIdType(),
+                                     Kind).get();
+      }
+      ReceiverType = Receiver->getType();
+    } else if (getLangOpts().CPlusPlus) {
+      // The receiver must be a complete type.
+      if (RequireCompleteType(Loc, Receiver->getType(),
+                              diag::err_incomplete_receiver_type))
+        return ExprError();
+
+      ExprResult result = PerformContextuallyConvertToObjCPointer(Receiver);
+      if (result.isUsable()) {
+        Receiver = result.get();
+        ReceiverType = Receiver->getType();
+      }
+    }
+  }
+
+  // There's a somewhat weird interaction here where we assume that we
+  // won't actually have a method unless we also don't need to do some
+  // of the more detailed type-checking on the receiver.
+
+  if (!Method) {
+    // Handle messages to id and __kindof types (where we use the
+    // global method pool).
+    const ObjCObjectType *typeBound = nullptr;
+    bool receiverIsIdLike = ReceiverType->isObjCIdOrObjectKindOfType(Context,
+                                                                     typeBound);
+    if (receiverIsIdLike || ReceiverType->isBlockPointerType() ||
+        (Receiver && Context.isObjCNSObjectType(Receiver->getType()))) {
+      SmallVector<ObjCMethodDecl*, 4> Methods;
+      // If we have a type bound, further filter the methods.
+      CollectMultipleMethodsInGlobalPool(Sel, Methods, true/*InstanceFirst*/,
+                                         true/*CheckTheOther*/, typeBound);
+      if (!Methods.empty()) {
+        // We choose the first method as the initial candidate, then try to
+        // select a better one.
+        Method = Methods[0];
+
+        if (ObjCMethodDecl *BestMethod =
+            SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(), Methods))
+          Method = BestMethod;
+
+        if (!AreMultipleMethodsInGlobalPool(Sel, Method,
+                                            SourceRange(LBracLoc, RBracLoc),
+                                            receiverIsIdLike, Methods))
+          DiagnoseUseOfDecl(Method, SelectorSlotLocs);
+      }
+    } else if (ReceiverType->isObjCClassOrClassKindOfType() ||
+               ReceiverType->isObjCQualifiedClassType()) {
+      // Handle messages to Class.
+      // We allow sending a message to a qualified Class ("Class<foo>"), which
+      // is ok as long as one of the protocols implements the selector (if not,
+      // warn).
+      if (!ReceiverType->isObjCClassOrClassKindOfType()) {
+        const ObjCObjectPointerType *QClassTy
+          = ReceiverType->getAsObjCQualifiedClassType();
+        // Search protocols for class methods.
+        Method = LookupMethodInQualifiedType(Sel, QClassTy, false);
+        if (!Method) {
+          Method = LookupMethodInQualifiedType(Sel, QClassTy, true);
+          // warn if instance method found for a Class message.
+          if (Method && !isMethodDeclaredInRootProtocol(*this, Method)) {
+            Diag(SelLoc, diag::warn_instance_method_on_class_found)
+              << Method->getSelector() << Sel;
+            Diag(Method->getLocation(), diag::note_method_declared_at)
+              << Method->getDeclName();
+          }
+        }
+      } else {
+        if (ObjCMethodDecl *CurMeth = getCurMethodDecl()) {
+          if (ObjCInterfaceDecl *ClassDecl = CurMeth->getClassInterface()) {
+            // As a guess, try looking for the method in the current interface.
+            // This very well may not produce the "right" method.
+
+            // First check the public methods in the class interface.
+            Method = ClassDecl->lookupClassMethod(Sel);
+
+            if (!Method)
+              Method = ClassDecl->lookupPrivateClassMethod(Sel);
+
+            if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
+              return ExprError();
+          }
+        }
+        if (!Method) {
+          // If not messaging 'self', look for any factory method named 'Sel'.
+          if (!Receiver || !isSelfExpr(Receiver)) {
+            // If no class (factory) method was found, check if an _instance_
+            // method of the same name exists in the root class only.
+            SmallVector<ObjCMethodDecl*, 4> Methods;
+            CollectMultipleMethodsInGlobalPool(Sel, Methods,
+                                               false/*InstanceFirst*/,
+                                               true/*CheckTheOther*/);
+            if (!Methods.empty()) {
+              // We choose the first method as the initial candidate, then try
+              // to select a better one.
+              Method = Methods[0];
+
+              // If we find an instance method, emit warning.
+              if (Method->isInstanceMethod()) {
+                if (const ObjCInterfaceDecl *ID =
+                    dyn_cast<ObjCInterfaceDecl>(Method->getDeclContext())) {
+                  if (ID->getSuperClass())
+                    Diag(SelLoc, diag::warn_root_inst_method_not_found)
+                        << Sel << SourceRange(LBracLoc, RBracLoc);
+                }
+              }
+
+             if (ObjCMethodDecl *BestMethod =
+                 SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
+                                  Methods))
+               Method = BestMethod;
+            }
+          }
+        }
+      }
+    } else {
+      ObjCInterfaceDecl *ClassDecl = nullptr;
+
+      // We allow sending a message to a qualified ID ("id<foo>"), which is ok as
+      // long as one of the protocols implements the selector (if not, warn).
+      // And as long as message is not deprecated/unavailable (warn if it is).
+      if (const ObjCObjectPointerType *QIdTy
+                                   = ReceiverType->getAsObjCQualifiedIdType()) {
+        // Search protocols for instance methods.
+        Method = LookupMethodInQualifiedType(Sel, QIdTy, true);
+        if (!Method)
+          Method = LookupMethodInQualifiedType(Sel, QIdTy, false);
+        if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs))
+          return ExprError();
+      } else if (const ObjCObjectPointerType *OCIType
+                   = ReceiverType->getAsObjCInterfacePointerType()) {
+        // We allow sending a message to a pointer to an interface (an object).
+        ClassDecl = OCIType->getInterfaceDecl();
+
+        // Try to complete the type. Under ARC, this is a hard error from which
+        // we don't try to recover.
+        // FIXME: In the non-ARC case, this will still be a hard error if the
+        // definition is found in a module that's not visible.
+        const ObjCInterfaceDecl *forwardClass = nullptr;
+        if (RequireCompleteType(Loc, OCIType->getPointeeType(),
+                                getLangOpts().ObjCAutoRefCount
+                                    ? diag::err_arc_receiver_forward_instance
+                                    : diag::warn_receiver_forward_instance,
+                                RecRange)) {
+          if (getLangOpts().ObjCAutoRefCount)
+            return ExprError();
+
+          forwardClass = OCIType->getInterfaceDecl();
+          Diag(Receiver ? Receiver->getBeginLoc() : SuperLoc,
+               diag::note_receiver_is_id);
+          Method = nullptr;
+        } else {
+          Method = ClassDecl->lookupInstanceMethod(Sel);
+        }
+
+        if (!Method)
+          // Search protocol qualifiers.
+          Method = LookupMethodInQualifiedType(Sel, OCIType, true);
+
+        if (!Method) {
+          // If we have implementations in scope, check "private" methods.
+          Method = ClassDecl->lookupPrivateMethod(Sel);
+
+          if (!Method && getLangOpts().ObjCAutoRefCount) {
+            Diag(SelLoc, diag::err_arc_may_not_respond)
+              << OCIType->getPointeeType() << Sel << RecRange
+              << SourceRange(SelectorLocs.front(), SelectorLocs.back());
+            return ExprError();
+          }
+
+          if (!Method && (!Receiver || !isSelfExpr(Receiver))) {
+            // If we still haven't found a method, look in the global pool. This
+            // behavior isn't very desirable, however we need it for GCC
+            // compatibility. FIXME: should we deviate??
+            if (OCIType->qual_empty()) {
+              SmallVector<ObjCMethodDecl*, 4> Methods;
+              CollectMultipleMethodsInGlobalPool(Sel, Methods,
+                                                 true/*InstanceFirst*/,
+                                                 false/*CheckTheOther*/);
+              if (!Methods.empty()) {
+                // We choose the first method as the initial candidate, then try
+                // to select a better one.
+                Method = Methods[0];
+
+                if (ObjCMethodDecl *BestMethod =
+                    SelectBestMethod(Sel, ArgsIn, Method->isInstanceMethod(),
+                                     Methods))
+                  Method = BestMethod;
+
+                AreMultipleMethodsInGlobalPool(Sel, Method,
+                                               SourceRange(LBracLoc, RBracLoc),
+                                               true/*receiverIdOrClass*/,
+                                               Methods);
+              }
+              if (Method && !forwardClass)
+                Diag(SelLoc, diag::warn_maynot_respond)
+                  << OCIType->getInterfaceDecl()->getIdentifier()
+                  << Sel << RecRange;
+            }
+          }
+        }
+        if (Method && DiagnoseUseOfDecl(Method, SelectorSlotLocs, forwardClass))
+          return ExprError();
+      } else {
+        // Reject other random receiver types (e.g. structs).
+        Diag(Loc, diag::err_bad_receiver_type) << ReceiverType << RecRange;
+        return ExprError();
+      }
+    }
+  }
+
+  FunctionScopeInfo *DIFunctionScopeInfo =
+    (Method && Method->getMethodFamily() == OMF_init)
+      ? getEnclosingFunction() : nullptr;
+
+  if (Method && Method->isDirectMethod()) {
+    if (ReceiverType->isObjCIdType() && !isImplicit) {
+      Diag(Receiver->getExprLoc(),
+           diag::err_messaging_unqualified_id_with_direct_method);
+      Diag(Method->getLocation(), diag::note_direct_method_declared_at)
+          << Method->getDeclName();
+    }
+
+    // Under ARC, self can't be assigned, and doing a direct call to `self`
+    // when it's a Class is hence safe.  For other cases, we can't trust `self`
+    // is what we think it is, so we reject it.
+    if (ReceiverType->isObjCClassType() && !isImplicit &&
+        !(Receiver->isObjCSelfExpr() && getLangOpts().ObjCAutoRefCount)) {
+      {
+        auto Builder = Diag(Receiver->getExprLoc(),
+                            diag::err_messaging_class_with_direct_method);
+        if (Receiver->isObjCSelfExpr()) {
+          Builder.AddFixItHint(FixItHint::CreateReplacement(
+              RecRange, Method->getClassInterface()->getName()));
+        }
+      }
+      Diag(Method->getLocation(), diag::note_direct_method_declared_at)
+          << Method->getDeclName();
+    }
+
+    if (SuperLoc.isValid()) {
+      {
+        auto Builder =
+            Diag(SuperLoc, diag::err_messaging_super_with_direct_method);
+        if (ReceiverType->isObjCClassType()) {
+          Builder.AddFixItHint(FixItHint::CreateReplacement(
+              SuperLoc, Method->getClassInterface()->getName()));
+        } else {
+          Builder.AddFixItHint(FixItHint::CreateReplacement(SuperLoc, "self"));
+        }
+      }
+      Diag(Method->getLocation(), diag::note_direct_method_declared_at)
+          << Method->getDeclName();
+    }
+  } else if (ReceiverType->isObjCIdType() && !isImplicit) {
+    Diag(Receiver->getExprLoc(), diag::warn_messaging_unqualified_id);
+  }
+
+  if (DIFunctionScopeInfo &&
+      DIFunctionScopeInfo->ObjCIsDesignatedInit &&
+      (SuperLoc.isValid() || isSelfExpr(Receiver))) {
+    bool isDesignatedInitChain = false;
+    if (SuperLoc.isValid()) {
+      if (const ObjCObjectPointerType *
+            OCIType = ReceiverType->getAsObjCInterfacePointerType()) {
+        if (const ObjCInterfaceDecl *ID = OCIType->getInterfaceDecl()) {
+          // Either we know this is a designated initializer or we
+          // conservatively assume it because we don't know for sure.
+          if (!ID->declaresOrInheritsDesignatedInitializers() ||
+              ID->isDesignatedInitializer(Sel)) {
+            isDesignatedInitChain = true;
+            DIFunctionScopeInfo->ObjCWarnForNoDesignatedInitChain = false;
+          }
+        }
+      }
+    }
+    if (!isDesignatedInitChain) {
+      const ObjCMethodDecl *InitMethod = nullptr;
+      bool isDesignated =
+        getCurMethodDecl()->isDesignatedInitializerForTheInterface(&InitMethod);
+      assert(isDesignated && InitMethod);
+      (void)isDesignated;
+      Diag(SelLoc, SuperLoc.isValid() ?
+             diag::warn_objc_designated_init_non_designated_init_call :
+             diag::warn_objc_designated_init_non_super_designated_init_call);
+      Diag(InitMethod->getLocation(),
+           diag::note_objc_designated_init_marked_here);
+    }
+  }
+
+  if (DIFunctionScopeInfo &&
+      DIFunctionScopeInfo->ObjCIsSecondaryInit &&
+      (SuperLoc.isValid() || isSelfExpr(Receiver))) {
+    if (SuperLoc.isValid()) {
+      Diag(SelLoc, diag::warn_objc_secondary_init_super_init_call);
+    } else {
+      DIFunctionScopeInfo->ObjCWarnForNoInitDelegation = false;
+    }
+  }
+
+  // Check the message arguments.
+  unsigned NumArgs = ArgsIn.size();
+  Expr **Args = ArgsIn.data();
+  QualType ReturnType;
+  ExprValueKind VK = VK_PRValue;
+  bool ClassMessage = (ReceiverType->isObjCClassType() ||
+                       ReceiverType->isObjCQualifiedClassType());
+  if (CheckMessageArgumentTypes(Receiver, ReceiverType,
+                                MultiExprArg(Args, NumArgs), Sel, SelectorLocs,
+                                Method, ClassMessage, SuperLoc.isValid(),
+                                LBracLoc, RBracLoc, RecRange, ReturnType, VK))
+    return ExprError();
+
+  if (Method && !Method->getReturnType()->isVoidType() &&
+      RequireCompleteType(LBracLoc, Method->getReturnType(),
+                          diag::err_illegal_message_expr_incomplete_type))
+    return ExprError();
+
+  // In ARC, forbid the user from sending messages to
+  // retain/release/autorelease/dealloc/retainCount explicitly.
+  if (getLangOpts().ObjCAutoRefCount) {
+    ObjCMethodFamily family =
+      (Method ? Method->getMethodFamily() : Sel.getMethodFamily());
+    switch (family) {
+    case OMF_init:
+      if (Method)
+        checkInitMethod(Method, ReceiverType);
+      break;
+
+    case OMF_None:
+    case OMF_alloc:
+    case OMF_copy:
+    case OMF_finalize:
+    case OMF_mutableCopy:
+    case OMF_new:
+    case OMF_self:
+    case OMF_initialize:
+      break;
+
+    case OMF_dealloc:
+    case OMF_retain:
+    case OMF_release:
+    case OMF_autorelease:
+    case OMF_retainCount:
+      Diag(SelLoc, diag::err_arc_illegal_explicit_message)
+        << Sel << RecRange;
+      break;
+
+    case OMF_performSelector:
+      if (Method && NumArgs >= 1) {
+        if (const auto *SelExp =
+                dyn_cast<ObjCSelectorExpr>(Args[0]->IgnoreParens())) {
+          Selector ArgSel = SelExp->getSelector();
+          ObjCMethodDecl *SelMethod =
+            LookupInstanceMethodInGlobalPool(ArgSel,
+                                             SelExp->getSourceRange());
+          if (!SelMethod)
+            SelMethod =
+              LookupFactoryMethodInGlobalPool(ArgSel,
+                                              SelExp->getSourceRange());
+          if (SelMethod) {
+            ObjCMethodFamily SelFamily = SelMethod->getMethodFamily();
+            switch (SelFamily) {
+              case OMF_alloc:
+              case OMF_copy:
+              case OMF_mutableCopy:
+              case OMF_new:
+              case OMF_init:
+                // Issue error, unless ns_returns_not_retained.
+                if (!SelMethod->hasAttr<NSReturnsNotRetainedAttr>()) {
+                  // selector names a +1 method
+                  Diag(SelLoc,
+                       diag::err_arc_perform_selector_retains);
+                  Diag(SelMethod->getLocation(), diag::note_method_declared_at)
+                    << SelMethod->getDeclName();
+                }
+                break;
+              default:
+                // +0 call. OK. unless ns_returns_retained.
+                if (SelMethod->hasAttr<NSReturnsRetainedAttr>()) {
+                  // selector names a +1 method
+                  Diag(SelLoc,
+                       diag::err_arc_perform_selector_retains);
+                  Diag(SelMethod->getLocation(), diag::note_method_declared_at)
+                    << SelMethod->getDeclName();
+                }
+                break;
+            }
+          }
+        } else {
+          // error (may leak).
+          Diag(SelLoc, diag::warn_arc_perform_selector_leaks);
+          Diag(Args[0]->getExprLoc(), diag::note_used_here);
+        }
+      }
+      break;
+    }
+  }
+
+  DiagnoseCStringFormatDirectiveInObjCAPI(*this, Method, Sel, Args, NumArgs);
+
+  // Construct the appropriate ObjCMessageExpr instance.
+  ObjCMessageExpr *Result;
+  if (SuperLoc.isValid())
+    Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
+                                     SuperLoc,  /*IsInstanceSuper=*/true,
+                                     ReceiverType, Sel, SelectorLocs, Method,
+                                     makeArrayRef(Args, NumArgs), RBracLoc,
+                                     isImplicit);
+  else {
+    Result = ObjCMessageExpr::Create(Context, ReturnType, VK, LBracLoc,
+                                     Receiver, Sel, SelectorLocs, Method,
+                                     makeArrayRef(Args, NumArgs), RBracLoc,
+                                     isImplicit);
+    if (!isImplicit)
+      checkCocoaAPI(*this, Result);
+  }
+  if (Method) {
+    bool IsClassObjectCall = ClassMessage;
+    // 'self' message receivers in class methods should be treated as message
+    // sends to the class object in order for the semantic checks to be
+    // performed correctly. Messages to 'super' already count as class messages,
+    // so they don't need to be handled here.
+    if (Receiver && isSelfExpr(Receiver)) {
+      if (const auto *OPT = ReceiverType->getAs<ObjCObjectPointerType>()) {
+        if (OPT->getObjectType()->isObjCClass()) {
+          if (const auto *CurMeth = getCurMethodDecl()) {
+            IsClassObjectCall = true;
+            ReceiverType =
+                Context.getObjCInterfaceType(CurMeth->getClassInterface());
+          }
+        }
+      }
+    }
+    checkFoundationAPI(*this, SelLoc, Method, makeArrayRef(Args, NumArgs),
+                       ReceiverType, IsClassObjectCall);
+  }
+
+  if (getLangOpts().ObjCAutoRefCount) {
+    // In ARC, annotate delegate init calls.
+    if (Result->getMethodFamily() == OMF_init &&
+        (SuperLoc.isValid() || isSelfExpr(Receiver))) {
+      // Only consider init calls *directly* in init implementations,
+      // not within blocks.
+      ObjCMethodDecl *method = dyn_cast<ObjCMethodDecl>(CurContext);
+      if (method && method->getMethodFamily() == OMF_init) {
+        // The implicit assignment to self means we also don't want to
+        // consume the result.
+        Result->setDelegateInitCall(true);
+        return Result;
+      }
+    }
+
+    // In ARC, check for message sends which are likely to introduce
+    // retain cycles.
+    checkRetainCycles(Result);
+  }
+
+  if (getLangOpts().ObjCWeak) {
+    if (!isImplicit && Method) {
+      if (const ObjCPropertyDecl *Prop = Method->findPropertyDecl()) {
+        bool IsWeak =
+            Prop->getPropertyAttributes() & ObjCPropertyAttribute::kind_weak;
+        if (!IsWeak && Sel.isUnarySelector())
+          IsWeak = ReturnType.getObjCLifetime() & Qualifiers::OCL_Weak;
+        if (IsWeak && !isUnevaluatedContext() &&
+            !Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, LBracLoc))
+          getCurFunction()->recordUseOfWeak(Result, Prop);
+      }
+    }
+  }
+
+  CheckObjCCircularContainer(Result);
+
+  return MaybeBindToTemporary(Result);
+}
+
+static void RemoveSelectorFromWarningCache(Sema &S, Expr* Arg) {
+  if (ObjCSelectorExpr *OSE =
+      dyn_cast<ObjCSelectorExpr>(Arg->IgnoreParenCasts())) {
+    Selector Sel = OSE->getSelector();
+    SourceLocation Loc = OSE->getAtLoc();
+    auto Pos = S.ReferencedSelectors.find(Sel);
+    if (Pos != S.ReferencedSelectors.end() && Pos->second == Loc)
+      S.ReferencedSelectors.erase(Pos);
+  }
+}
+
+// ActOnInstanceMessage - used for both unary and keyword messages.
+// ArgExprs is optional - if it is present, the number of expressions
+// is obtained from Sel.getNumArgs().
+ExprResult Sema::ActOnInstanceMessage(Scope *S,
+                                      Expr *Receiver,
+                                      Selector Sel,
+                                      SourceLocation LBracLoc,
+                                      ArrayRef<SourceLocation> SelectorLocs,
+                                      SourceLocation RBracLoc,
+                                      MultiExprArg Args) {
+  if (!Receiver)
+    return ExprError();
+
+  // A ParenListExpr can show up while doing error recovery with invalid code.
+  if (isa<ParenListExpr>(Receiver)) {
+    ExprResult Result = MaybeConvertParenListExprToParenExpr(S, Receiver);
+    if (Result.isInvalid()) return ExprError();
+    Receiver = Result.get();
+  }
+
+  if (RespondsToSelectorSel.isNull()) {
+    IdentifierInfo *SelectorId = &Context.Idents.get("respondsToSelector");
+    RespondsToSelectorSel = Context.Selectors.getUnarySelector(SelectorId);
+  }
+  if (Sel == RespondsToSelectorSel)
+    RemoveSelectorFromWarningCache(*this, Args[0]);
+
+  return BuildInstanceMessage(Receiver, Receiver->getType(),
+                              /*SuperLoc=*/SourceLocation(), Sel,
+                              /*Method=*/nullptr, LBracLoc, SelectorLocs,
+                              RBracLoc, Args);
+}
+
+enum ARCConversionTypeClass {
+  /// int, void, struct A
+  ACTC_none,
+
+  /// id, void (^)()
+  ACTC_retainable,
+
+  /// id*, id***, void (^*)(),
+  ACTC_indirectRetainable,
+
+  /// void* might be a normal C type, or it might a CF type.
+  ACTC_voidPtr,
+
+  /// struct A*
+  ACTC_coreFoundation
+};
+
+static bool isAnyRetainable(ARCConversionTypeClass ACTC) {
+  return (ACTC == ACTC_retainable ||
+          ACTC == ACTC_coreFoundation ||
+          ACTC == ACTC_voidPtr);
+}
+
+static bool isAnyCLike(ARCConversionTypeClass ACTC) {
+  return ACTC == ACTC_none ||
+         ACTC == ACTC_voidPtr ||
+         ACTC == ACTC_coreFoundation;
+}
+
+static ARCConversionTypeClass classifyTypeForARCConversion(QualType type) {
+  bool isIndirect = false;
+
+  // Ignore an outermost reference type.
+  if (const ReferenceType *ref = type->getAs<ReferenceType>()) {
+    type = ref->getPointeeType();
+    isIndirect = true;
+  }
+
+  // Drill through pointers and arrays recursively.
+  while (true) {
+    if (const PointerType *ptr = type->getAs<PointerType>()) {
+      type = ptr->getPointeeType();
+
+      // The first level of pointer may be the innermost pointer on a CF type.
+      if (!isIndirect) {
+        if (type->isVoidType()) return ACTC_voidPtr;
+        if (type->isRecordType()) return ACTC_coreFoundation;
+      }
+    } else if (const ArrayType *array = type->getAsArrayTypeUnsafe()) {
+      type = QualType(array->getElementType()->getBaseElementTypeUnsafe(), 0);
+    } else {
+      break;
+    }
+    isIndirect = true;
+  }
+
+  if (isIndirect) {
+    if (type->isObjCARCBridgableType())
+      return ACTC_indirectRetainable;
+    return ACTC_none;
+  }
+
+  if (type->isObjCARCBridgableType())
+    return ACTC_retainable;
+
+  return ACTC_none;
+}
+
+namespace {
+  /// A result from the cast checker.
+  enum ACCResult {
+    /// Cannot be casted.
+    ACC_invalid,
+
+    /// Can be safely retained or not retained.
+    ACC_bottom,
+
+    /// Can be casted at +0.
+    ACC_plusZero,
+
+    /// Can be casted at +1.
+    ACC_plusOne
+  };
+  ACCResult merge(ACCResult left, ACCResult right) {
+    if (left == right) return left;
+    if (left == ACC_bottom) return right;
+    if (right == ACC_bottom) return left;
+    return ACC_invalid;
+  }
+
+  /// A checker which white-lists certain expressions whose conversion
+  /// to or from retainable type would otherwise be forbidden in ARC.
+  class ARCCastChecker : public StmtVisitor<ARCCastChecker, ACCResult> {
+    typedef StmtVisitor<ARCCastChecker, ACCResult> super;
+
+    ASTContext &Context;
+    ARCConversionTypeClass SourceClass;
+    ARCConversionTypeClass TargetClass;
+    bool Diagnose;
+
+    static bool isCFType(QualType type) {
+      // Someday this can use ns_bridged.  For now, it has to do this.
+      return type->isCARCBridgableType();
+    }
+
+  public:
+    ARCCastChecker(ASTContext &Context, ARCConversionTypeClass source,
+                   ARCConversionTypeClass target, bool diagnose)
+      : Context(Context), SourceClass(source), TargetClass(target),
+        Diagnose(diagnose) {}
+
+    using super::Visit;
+    ACCResult Visit(Expr *e) {
+      return super::Visit(e->IgnoreParens());
+    }
+
+    ACCResult VisitStmt(Stmt *s) {
+      return ACC_invalid;
+    }
+
+    /// Null pointer constants can be casted however you please.
+    ACCResult VisitExpr(Expr *e) {
+      if (e->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull))
+        return ACC_bottom;
+      return ACC_invalid;
+    }
+
+    /// Objective-C string literals can be safely casted.
+    ACCResult VisitObjCStringLiteral(ObjCStringLiteral *e) {
+      // If we're casting to any retainable type, go ahead.  Global
+      // strings are immune to retains, so this is bottom.
+      if (isAnyRetainable(TargetClass)) return ACC_bottom;
+
+      return ACC_invalid;
+    }
+
+    /// Look through certain implicit and explicit casts.
+    ACCResult VisitCastExpr(CastExpr *e) {
+      switch (e->getCastKind()) {
+        case CK_NullToPointer:
+          return ACC_bottom;
+
+        case CK_NoOp:
+        case CK_LValueToRValue:
+        case CK_BitCast:
+        case CK_CPointerToObjCPointerCast:
+        case CK_BlockPointerToObjCPointerCast:
+        case CK_AnyPointerToBlockPointerCast:
+          return Visit(e->getSubExpr());
+
+        default:
+          return ACC_invalid;
+      }
+    }
+
+    /// Look through unary extension.
+    ACCResult VisitUnaryExtension(UnaryOperator *e) {
+      return Visit(e->getSubExpr());
+    }
+
+    /// Ignore the LHS of a comma operator.
+    ACCResult VisitBinComma(BinaryOperator *e) {
+      return Visit(e->getRHS());
+    }
+
+    /// Conditional operators are okay if both sides are okay.
+    ACCResult VisitConditionalOperator(ConditionalOperator *e) {
+      ACCResult left = Visit(e->getTrueExpr());
+      if (left == ACC_invalid) return ACC_invalid;
+      return merge(left, Visit(e->getFalseExpr()));
+    }
+
+    /// Look through pseudo-objects.
+    ACCResult VisitPseudoObjectExpr(PseudoObjectExpr *e) {
+      // If we're getting here, we should always have a result.
+      return Visit(e->getResultExpr());
+    }
+
+    /// Statement expressions are okay if their result expression is okay.
+    ACCResult VisitStmtExpr(StmtExpr *e) {
+      return Visit(e->getSubStmt()->body_back());
+    }
+
+    /// Some declaration references are okay.
+    ACCResult VisitDeclRefExpr(DeclRefExpr *e) {
+      VarDecl *var = dyn_cast<VarDecl>(e->getDecl());
+      // References to global constants are okay.
+      if (isAnyRetainable(TargetClass) &&
+          isAnyRetainable(SourceClass) &&
+          var &&
+          !var->hasDefinition(Context) &&
+          var->getType().isConstQualified()) {
+
+        // In system headers, they can also be assumed to be immune to retains.
+        // These are things like 'kCFStringTransformToLatin'.
+        if (Context.getSourceManager().isInSystemHeader(var->getLocation()))
+          return ACC_bottom;
+
+        return ACC_plusZero;
+      }
+
+      // Nothing else.
+      return ACC_invalid;
+    }
+
+    /// Some calls are okay.
+    ACCResult VisitCallExpr(CallExpr *e) {
+      if (FunctionDecl *fn = e->getDirectCallee())
+        if (ACCResult result = checkCallToFunction(fn))
+          return result;
+
+      return super::VisitCallExpr(e);
+    }
+
+    ACCResult checkCallToFunction(FunctionDecl *fn) {
+      // Require a CF*Ref return type.
+      if (!isCFType(fn->getReturnType()))
+        return ACC_invalid;
+
+      if (!isAnyRetainable(TargetClass))
+        return ACC_invalid;
+
+      // Honor an explicit 'not retained' attribute.
+      if (fn->hasAttr<CFReturnsNotRetainedAttr>())
+        return ACC_plusZero;
+
+      // Honor an explicit 'retained' attribute, except that for
+      // now we're not going to permit implicit handling of +1 results,
+      // because it's a bit frightening.
+      if (fn->hasAttr<CFReturnsRetainedAttr>())
+        return Diagnose ? ACC_plusOne
+                        : ACC_invalid; // ACC_plusOne if we start accepting this
+
+      // Recognize this specific builtin function, which is used by CFSTR.
+      unsigned builtinID = fn->getBuiltinID();
+      if (builtinID == Builtin::BI__builtin___CFStringMakeConstantString)
+        return ACC_bottom;
+
+      // Otherwise, don't do anything implicit with an unaudited function.
+      if (!fn->hasAttr<CFAuditedTransferAttr>())
+        return ACC_invalid;
+
+      // Otherwise, it's +0 unless it follows the create convention.
+      if (ento::coreFoundation::followsCreateRule(fn))
+        return Diagnose ? ACC_plusOne
+                        : ACC_invalid; // ACC_plusOne if we start accepting this
+
+      return ACC_plusZero;
+    }
+
+    ACCResult VisitObjCMessageExpr(ObjCMessageExpr *e) {
+      return checkCallToMethod(e->getMethodDecl());
+    }
+
+    ACCResult VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *e) {
+      ObjCMethodDecl *method;
+      if (e->isExplicitProperty())
+        method = e->getExplicitProperty()->getGetterMethodDecl();
+      else
+        method = e->getImplicitPropertyGetter();
+      return checkCallToMethod(method);
+    }
+
+    ACCResult checkCallToMethod(ObjCMethodDecl *method) {
+      if (!method) return ACC_invalid;
+
+      // Check for message sends to functions returning CF types.  We
+      // just obey the Cocoa conventions with these, even though the
+      // return type is CF.
+      if (!isAnyRetainable(TargetClass) || !isCFType(method->getReturnType()))
+        return ACC_invalid;
+
+      // If the method is explicitly marked not-retained, it's +0.
+      if (method->hasAttr<CFReturnsNotRetainedAttr>())
+        return ACC_plusZero;
+
+      // If the method is explicitly marked as returning retained, or its
+      // selector follows a +1 Cocoa convention, treat it as +1.
+      if (method->hasAttr<CFReturnsRetainedAttr>())
+        return ACC_plusOne;
+
+      switch (method->getSelector().getMethodFamily()) {
+      case OMF_alloc:
+      case OMF_copy:
+      case OMF_mutableCopy:
+      case OMF_new:
+        return ACC_plusOne;
+
+      default:
+        // Otherwise, treat it as +0.
+        return ACC_plusZero;
+      }
+    }
+  };
+} // end anonymous namespace
+
+bool Sema::isKnownName(StringRef name) {
+  if (name.empty())
+    return false;
+  LookupResult R(*this, &Context.Idents.get(name), SourceLocation(),
+                 Sema::LookupOrdinaryName);
+  return LookupName(R, TUScope, false);
+}
+
+template <typename DiagBuilderT>
+static void addFixitForObjCARCConversion(
+    Sema &S, DiagBuilderT &DiagB, Sema::CheckedConversionKind CCK,
+    SourceLocation afterLParen, QualType castType, Expr *castExpr,
+    Expr *realCast, const char *bridgeKeyword, const char *CFBridgeName) {
+  // We handle C-style and implicit casts here.
+  switch (CCK) {
+  case Sema::CCK_ImplicitConversion:
+  case Sema::CCK_ForBuiltinOverloadedOp:
+  case Sema::CCK_CStyleCast:
+  case Sema::CCK_OtherCast:
+    break;
+  case Sema::CCK_FunctionalCast:
+    return;
+  }
+
+  if (CFBridgeName) {
+    if (CCK == Sema::CCK_OtherCast) {
+      if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
+        SourceRange range(NCE->getOperatorLoc(),
+                          NCE->getAngleBrackets().getEnd());
+        SmallString<32> BridgeCall;
+
+        SourceManager &SM = S.getSourceManager();
+        char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
+        if (Lexer::isAsciiIdentifierContinueChar(PrevChar, S.getLangOpts()))
+          BridgeCall += ' ';
+
+        BridgeCall += CFBridgeName;
+        DiagB.AddFixItHint(FixItHint::CreateReplacement(range, BridgeCall));
+      }
+      return;
+    }
+    Expr *castedE = castExpr;
+    if (CStyleCastExpr *CCE = dyn_cast<CStyleCastExpr>(castedE))
+      castedE = CCE->getSubExpr();
+    castedE = castedE->IgnoreImpCasts();
+    SourceRange range = castedE->getSourceRange();
+
+    SmallString<32> BridgeCall;
+
+    SourceManager &SM = S.getSourceManager();
+    char PrevChar = *SM.getCharacterData(range.getBegin().getLocWithOffset(-1));
+    if (Lexer::isAsciiIdentifierContinueChar(PrevChar, S.getLangOpts()))
+      BridgeCall += ' ';
+
+    BridgeCall += CFBridgeName;
+
+    if (isa<ParenExpr>(castedE)) {
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
+                         BridgeCall));
+    } else {
+      BridgeCall += '(';
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
+                                                    BridgeCall));
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(
+                                       S.getLocForEndOfToken(range.getEnd()),
+                                       ")"));
+    }
+    return;
+  }
+
+  if (CCK == Sema::CCK_CStyleCast) {
+    DiagB.AddFixItHint(FixItHint::CreateInsertion(afterLParen, bridgeKeyword));
+  } else if (CCK == Sema::CCK_OtherCast) {
+    if (const CXXNamedCastExpr *NCE = dyn_cast<CXXNamedCastExpr>(realCast)) {
+      std::string castCode = "(";
+      castCode += bridgeKeyword;
+      castCode += castType.getAsString();
+      castCode += ")";
+      SourceRange Range(NCE->getOperatorLoc(),
+                        NCE->getAngleBrackets().getEnd());
+      DiagB.AddFixItHint(FixItHint::CreateReplacement(Range, castCode));
+    }
+  } else {
+    std::string castCode = "(";
+    castCode += bridgeKeyword;
+    castCode += castType.getAsString();
+    castCode += ")";
+    Expr *castedE = castExpr->IgnoreImpCasts();
+    SourceRange range = castedE->getSourceRange();
+    if (isa<ParenExpr>(castedE)) {
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
+                         castCode));
+    } else {
+      castCode += "(";
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(range.getBegin(),
+                                                    castCode));
+      DiagB.AddFixItHint(FixItHint::CreateInsertion(
+                                       S.getLocForEndOfToken(range.getEnd()),
+                                       ")"));
+    }
+  }
+}
+
+template <typename T>
+static inline T *getObjCBridgeAttr(const TypedefType *TD) {
+  TypedefNameDecl *TDNDecl = TD->getDecl();
+  QualType QT = TDNDecl->getUnderlyingType();
+  if (QT->isPointerType()) {
+    QT = QT->getPointeeType();
+    if (const RecordType *RT = QT->getAs<RecordType>()) {
+      for (auto *Redecl : RT->getDecl()->getMostRecentDecl()->redecls()) {
+        if (auto *attr = Redecl->getAttr<T>())
+          return attr;
+      }
+    }
+  }
+  return nullptr;
+}
+
+static ObjCBridgeRelatedAttr *ObjCBridgeRelatedAttrFromType(QualType T,
+                                                            TypedefNameDecl *&TDNDecl) {
+  while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
+    TDNDecl = TD->getDecl();
+    if (ObjCBridgeRelatedAttr *ObjCBAttr =
+        getObjCBridgeAttr<ObjCBridgeRelatedAttr>(TD))
+      return ObjCBAttr;
+    T = TDNDecl->getUnderlyingType();
+  }
+  return nullptr;
+}
+
+static void
+diagnoseObjCARCConversion(Sema &S, SourceRange castRange,
+                          QualType castType, ARCConversionTypeClass castACTC,
+                          Expr *castExpr, Expr *realCast,
+                          ARCConversionTypeClass exprACTC,
+                          Sema::CheckedConversionKind CCK) {
+  SourceLocation loc =
+    (castRange.isValid() ? castRange.getBegin() : castExpr->getExprLoc());
+
+  if (S.makeUnavailableInSystemHeader(loc,
+                                 UnavailableAttr::IR_ARCForbiddenConversion))
+    return;
+
+  QualType castExprType = castExpr->getType();
+  // Defer emitting a diagnostic for bridge-related casts; that will be
+  // handled by CheckObjCBridgeRelatedConversions.
+  TypedefNameDecl *TDNDecl = nullptr;
+  if ((castACTC == ACTC_coreFoundation &&  exprACTC == ACTC_retainable &&
+       ObjCBridgeRelatedAttrFromType(castType, TDNDecl)) ||
+      (exprACTC == ACTC_coreFoundation && castACTC == ACTC_retainable &&
+       ObjCBridgeRelatedAttrFromType(castExprType, TDNDecl)))
+    return;
+
+  unsigned srcKind = 0;
+  switch (exprACTC) {
+  case ACTC_none:
+  case ACTC_coreFoundation:
+  case ACTC_voidPtr:
+    srcKind = (castExprType->isPointerType() ? 1 : 0);
+    break;
+  case ACTC_retainable:
+    srcKind = (castExprType->isBlockPointerType() ? 2 : 3);
+    break;
+  case ACTC_indirectRetainable:
+    srcKind = 4;
+    break;
+  }
+
+  // Check whether this could be fixed with a bridge cast.
+  SourceLocation afterLParen = S.getLocForEndOfToken(castRange.getBegin());
+  SourceLocation noteLoc = afterLParen.isValid() ? afterLParen : loc;
+
+  unsigned convKindForDiag = Sema::isCast(CCK) ? 0 : 1;
+
+  // Bridge from an ARC type to a CF type.
+  if (castACTC == ACTC_retainable && isAnyRetainable(exprACTC)) {
+
+    S.Diag(loc, diag::err_arc_cast_requires_bridge)
+      << convKindForDiag
+      << 2 // of C pointer type
+      << castExprType
+      << unsigned(castType->isBlockPointerType()) // to ObjC|block type
+      << castType
+      << castRange
+      << castExpr->getSourceRange();
+    bool br = S.isKnownName("CFBridgingRelease");
+    ACCResult CreateRule =
+      ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
+    assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
+    if (CreateRule != ACC_plusOne)
+    {
+      auto DiagB = (CCK != Sema::CCK_OtherCast)
+                       ? S.Diag(noteLoc, diag::note_arc_bridge)
+                       : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
+
+      addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
+                                   castType, castExpr, realCast, "__bridge ",
+                                   nullptr);
+    }
+    if (CreateRule != ACC_plusZero)
+    {
+      auto DiagB = (CCK == Sema::CCK_OtherCast && !br)
+                       ? S.Diag(noteLoc, diag::note_arc_cstyle_bridge_transfer)
+                             << castExprType
+                       : S.Diag(br ? castExpr->getExprLoc() : noteLoc,
+                                diag::note_arc_bridge_transfer)
+                             << castExprType << br;
+
+      addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
+                                   castType, castExpr, realCast, "__bridge_transfer ",
+                                   br ? "CFBridgingRelease" : nullptr);
+    }
+
+    return;
+  }
+
+  // Bridge from a CF type to an ARC type.
+  if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC)) {
+    bool br = S.isKnownName("CFBridgingRetain");
+    S.Diag(loc, diag::err_arc_cast_requires_bridge)
+      << convKindForDiag
+      << unsigned(castExprType->isBlockPointerType()) // of ObjC|block type
+      << castExprType
+      << 2 // to C pointer type
+      << castType
+      << castRange
+      << castExpr->getSourceRange();
+    ACCResult CreateRule =
+      ARCCastChecker(S.Context, exprACTC, castACTC, true).Visit(castExpr);
+    assert(CreateRule != ACC_bottom && "This cast should already be accepted.");
+    if (CreateRule != ACC_plusOne)
+    {
+      auto DiagB = (CCK != Sema::CCK_OtherCast)
+                       ? S.Diag(noteLoc, diag::note_arc_bridge)
+                       : S.Diag(noteLoc, diag::note_arc_cstyle_bridge);
+      addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
+                                   castType, castExpr, realCast, "__bridge ",
+                                   nullptr);
+    }
+    if (CreateRule != ACC_plusZero)
+    {
+      auto DiagB = (CCK == Sema::CCK_OtherCast && !br)
+                       ? S.Diag(noteLoc, diag::note_arc_cstyle_bridge_retained)
+                             << castType
+                       : S.Diag(br ? castExpr->getExprLoc() : noteLoc,
+                                diag::note_arc_bridge_retained)
+                             << castType << br;
+
+      addFixitForObjCARCConversion(S, DiagB, CCK, afterLParen,
+                                   castType, castExpr, realCast, "__bridge_retained ",
+                                   br ? "CFBridgingRetain" : nullptr);
+    }
+
+    return;
+  }
+
+  S.Diag(loc, diag::err_arc_mismatched_cast)
+    << !convKindForDiag
+    << srcKind << castExprType << castType
+    << castRange << castExpr->getSourceRange();
+}
+
+template <typename TB>
+static bool CheckObjCBridgeNSCast(Sema &S, QualType castType, Expr *castExpr,
+                                  bool &HadTheAttribute, bool warn) {
+  QualType T = castExpr->getType();
+  HadTheAttribute = false;
+  while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
+    TypedefNameDecl *TDNDecl = TD->getDecl();
+    if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
+      if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
+        HadTheAttribute = true;
+        if (Parm->isStr("id"))
+          return true;
+
+        // Check for an existing type with this name.
+        LookupResult R(S, DeclarationName(Parm), SourceLocation(),
+                       Sema::LookupOrdinaryName);
+        if (S.LookupName(R, S.TUScope)) {
+          NamedDecl *Target = R.getFoundDecl();
+          if (Target && isa<ObjCInterfaceDecl>(Target)) {
+            ObjCInterfaceDecl *ExprClass = cast<ObjCInterfaceDecl>(Target);
+            if (const ObjCObjectPointerType *InterfacePointerType =
+                  castType->getAsObjCInterfacePointerType()) {
+              ObjCInterfaceDecl *CastClass
+                = InterfacePointerType->getObjectType()->getInterface();
+              if ((CastClass == ExprClass) ||
+                  (CastClass && CastClass->isSuperClassOf(ExprClass)))
+                return true;
+              if (warn)
+                S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
+                    << T << Target->getName() << castType->getPointeeType();
+              return false;
+            } else if (castType->isObjCIdType() ||
+                       (S.Context.ObjCObjectAdoptsQTypeProtocols(
+                          castType, ExprClass)))
+              // ok to cast to 'id'.
+              // casting to id<p-list> is ok if bridge type adopts all of
+              // p-list protocols.
+              return true;
+            else {
+              if (warn) {
+                S.Diag(castExpr->getBeginLoc(), diag::warn_objc_invalid_bridge)
+                    << T << Target->getName() << castType;
+                S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+                S.Diag(Target->getBeginLoc(), diag::note_declared_at);
+              }
+              return false;
+           }
+          }
+        } else if (!castType->isObjCIdType()) {
+          S.Diag(castExpr->getBeginLoc(),
+                 diag::err_objc_cf_bridged_not_interface)
+              << castExpr->getType() << Parm;
+          S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+        }
+        return true;
+      }
+      return false;
+    }
+    T = TDNDecl->getUnderlyingType();
+  }
+  return true;
+}
+
+template <typename TB>
+static bool CheckObjCBridgeCFCast(Sema &S, QualType castType, Expr *castExpr,
+                                  bool &HadTheAttribute, bool warn) {
+  QualType T = castType;
+  HadTheAttribute = false;
+  while (const TypedefType *TD = dyn_cast<TypedefType>(T.getTypePtr())) {
+    TypedefNameDecl *TDNDecl = TD->getDecl();
+    if (TB *ObjCBAttr = getObjCBridgeAttr<TB>(TD)) {
+      if (IdentifierInfo *Parm = ObjCBAttr->getBridgedType()) {
+        HadTheAttribute = true;
+        if (Parm->isStr("id"))
+          return true;
+
+        NamedDecl *Target = nullptr;
+        // Check for an existing type with this name.
+        LookupResult R(S, DeclarationName(Parm), SourceLocation(),
+                       Sema::LookupOrdinaryName);
+        if (S.LookupName(R, S.TUScope)) {
+          Target = R.getFoundDecl();
+          if (Target && isa<ObjCInterfaceDecl>(Target)) {
+            ObjCInterfaceDecl *CastClass = cast<ObjCInterfaceDecl>(Target);
+            if (const ObjCObjectPointerType *InterfacePointerType =
+                  castExpr->getType()->getAsObjCInterfacePointerType()) {
+              ObjCInterfaceDecl *ExprClass
+                = InterfacePointerType->getObjectType()->getInterface();
+              if ((CastClass == ExprClass) ||
+                  (ExprClass && CastClass->isSuperClassOf(ExprClass)))
+                return true;
+              if (warn) {
+                S.Diag(castExpr->getBeginLoc(),
+                       diag::warn_objc_invalid_bridge_to_cf)
+                    << castExpr->getType()->getPointeeType() << T;
+                S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+              }
+              return false;
+            } else if (castExpr->getType()->isObjCIdType() ||
+                       (S.Context.QIdProtocolsAdoptObjCObjectProtocols(
+                          castExpr->getType(), CastClass)))
+              // ok to cast an 'id' expression to a CFtype.
+              // ok to cast an 'id<plist>' expression to CFtype provided plist
+              // adopts all of CFtype's ObjetiveC's class plist.
+              return true;
+            else {
+              if (warn) {
+                S.Diag(castExpr->getBeginLoc(),
+                       diag::warn_objc_invalid_bridge_to_cf)
+                    << castExpr->getType() << castType;
+                S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+                S.Diag(Target->getBeginLoc(), diag::note_declared_at);
+              }
+              return false;
+            }
+          }
+        }
+        S.Diag(castExpr->getBeginLoc(),
+               diag::err_objc_ns_bridged_invalid_cfobject)
+            << castExpr->getType() << castType;
+        S.Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+        if (Target)
+          S.Diag(Target->getBeginLoc(), diag::note_declared_at);
+        return true;
+      }
+      return false;
+    }
+    T = TDNDecl->getUnderlyingType();
+  }
+  return true;
+}
+
+void Sema::CheckTollFreeBridgeCast(QualType castType, Expr *castExpr) {
+  if (!getLangOpts().ObjC)
+    return;
+  // warn in presence of __bridge casting to or from a toll free bridge cast.
+  ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExpr->getType());
+  ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
+  if (castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) {
+    bool HasObjCBridgeAttr;
+    bool ObjCBridgeAttrWillNotWarn =
+      CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
+                                            false);
+    if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
+      return;
+    bool HasObjCBridgeMutableAttr;
+    bool ObjCBridgeMutableAttrWillNotWarn =
+      CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
+                                                   HasObjCBridgeMutableAttr, false);
+    if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
+      return;
+
+    if (HasObjCBridgeAttr)
+      CheckObjCBridgeNSCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
+                                            true);
+    else if (HasObjCBridgeMutableAttr)
+      CheckObjCBridgeNSCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
+                                                   HasObjCBridgeMutableAttr, true);
+  }
+  else if (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable) {
+    bool HasObjCBridgeAttr;
+    bool ObjCBridgeAttrWillNotWarn =
+      CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
+                                            false);
+    if (ObjCBridgeAttrWillNotWarn && HasObjCBridgeAttr)
+      return;
+    bool HasObjCBridgeMutableAttr;
+    bool ObjCBridgeMutableAttrWillNotWarn =
+      CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
+                                                   HasObjCBridgeMutableAttr, false);
+    if (ObjCBridgeMutableAttrWillNotWarn && HasObjCBridgeMutableAttr)
+      return;
+
+    if (HasObjCBridgeAttr)
+      CheckObjCBridgeCFCast<ObjCBridgeAttr>(*this, castType, castExpr, HasObjCBridgeAttr,
+                                            true);
+    else if (HasObjCBridgeMutableAttr)
+      CheckObjCBridgeCFCast<ObjCBridgeMutableAttr>(*this, castType, castExpr,
+                                                   HasObjCBridgeMutableAttr, true);
+  }
+}
+
+void Sema::CheckObjCBridgeRelatedCast(QualType castType, Expr *castExpr) {
+  QualType SrcType = castExpr->getType();
+  if (ObjCPropertyRefExpr *PRE = dyn_cast<ObjCPropertyRefExpr>(castExpr)) {
+    if (PRE->isExplicitProperty()) {
+      if (ObjCPropertyDecl *PDecl = PRE->getExplicitProperty())
+        SrcType = PDecl->getType();
+    }
+    else if (PRE->isImplicitProperty()) {
+      if (ObjCMethodDecl *Getter = PRE->getImplicitPropertyGetter())
+        SrcType = Getter->getReturnType();
+    }
+  }
+
+  ARCConversionTypeClass srcExprACTC = classifyTypeForARCConversion(SrcType);
+  ARCConversionTypeClass castExprACTC = classifyTypeForARCConversion(castType);
+  if (srcExprACTC != ACTC_retainable || castExprACTC != ACTC_coreFoundation)
+    return;
+  CheckObjCBridgeRelatedConversions(castExpr->getBeginLoc(), castType, SrcType,
+                                    castExpr);
+}
+
+bool Sema::CheckTollFreeBridgeStaticCast(QualType castType, Expr *castExpr,
+                                         CastKind &Kind) {
+  if (!getLangOpts().ObjC)
+    return false;
+  ARCConversionTypeClass exprACTC =
+    classifyTypeForARCConversion(castExpr->getType());
+  ARCConversionTypeClass castACTC = classifyTypeForARCConversion(castType);
+  if ((castACTC == ACTC_retainable && exprACTC == ACTC_coreFoundation) ||
+      (castACTC == ACTC_coreFoundation && exprACTC == ACTC_retainable)) {
+    CheckTollFreeBridgeCast(castType, castExpr);
+    Kind = (castACTC == ACTC_coreFoundation) ? CK_BitCast
+                                             : CK_CPointerToObjCPointerCast;
+    return true;
+  }
+  return false;
+}
+
+bool Sema::checkObjCBridgeRelatedComponents(SourceLocation Loc,
+                                            QualType DestType, QualType SrcType,
+                                            ObjCInterfaceDecl *&RelatedClass,
+                                            ObjCMethodDecl *&ClassMethod,
+                                            ObjCMethodDecl *&InstanceMethod,
+                                            TypedefNameDecl *&TDNDecl,
+                                            bool CfToNs, bool Diagnose) {
+  QualType T = CfToNs ? SrcType : DestType;
+  ObjCBridgeRelatedAttr *ObjCBAttr = ObjCBridgeRelatedAttrFromType(T, TDNDecl);
+  if (!ObjCBAttr)
+    return false;
+
+  IdentifierInfo *RCId = ObjCBAttr->getRelatedClass();
+  IdentifierInfo *CMId = ObjCBAttr->getClassMethod();
+  IdentifierInfo *IMId = ObjCBAttr->getInstanceMethod();
+  if (!RCId)
+    return false;
+  NamedDecl *Target = nullptr;
+  // Check for an existing type with this name.
+  LookupResult R(*this, DeclarationName(RCId), SourceLocation(),
+                 Sema::LookupOrdinaryName);
+  if (!LookupName(R, TUScope)) {
+    if (Diagnose) {
+      Diag(Loc, diag::err_objc_bridged_related_invalid_class) << RCId
+            << SrcType << DestType;
+      Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+    }
+    return false;
+  }
+  Target = R.getFoundDecl();
+  if (Target && isa<ObjCInterfaceDecl>(Target))
+    RelatedClass = cast<ObjCInterfaceDecl>(Target);
+  else {
+    if (Diagnose) {
+      Diag(Loc, diag::err_objc_bridged_related_invalid_class_name) << RCId
+            << SrcType << DestType;
+      Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+      if (Target)
+        Diag(Target->getBeginLoc(), diag::note_declared_at);
+    }
+    return false;
+  }
+
+  // Check for an existing class method with the given selector name.
+  if (CfToNs && CMId) {
+    Selector Sel = Context.Selectors.getUnarySelector(CMId);
+    ClassMethod = RelatedClass->lookupMethod(Sel, false);
+    if (!ClassMethod) {
+      if (Diagnose) {
+        Diag(Loc, diag::err_objc_bridged_related_known_method)
+              << SrcType << DestType << Sel << false;
+        Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+      }
+      return false;
+    }
+  }
+
+  // Check for an existing instance method with the given selector name.
+  if (!CfToNs && IMId) {
+    Selector Sel = Context.Selectors.getNullarySelector(IMId);
+    InstanceMethod = RelatedClass->lookupMethod(Sel, true);
+    if (!InstanceMethod) {
+      if (Diagnose) {
+        Diag(Loc, diag::err_objc_bridged_related_known_method)
+              << SrcType << DestType << Sel << true;
+        Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+      }
+      return false;
+    }
+  }
+  return true;
+}
+
+bool
+Sema::CheckObjCBridgeRelatedConversions(SourceLocation Loc,
+                                        QualType DestType, QualType SrcType,
+                                        Expr *&SrcExpr, bool Diagnose) {
+  ARCConversionTypeClass rhsExprACTC = classifyTypeForARCConversion(SrcType);
+  ARCConversionTypeClass lhsExprACTC = classifyTypeForARCConversion(DestType);
+  bool CfToNs = (rhsExprACTC == ACTC_coreFoundation && lhsExprACTC == ACTC_retainable);
+  bool NsToCf = (rhsExprACTC == ACTC_retainable && lhsExprACTC == ACTC_coreFoundation);
+  if (!CfToNs && !NsToCf)
+    return false;
+
+  ObjCInterfaceDecl *RelatedClass;
+  ObjCMethodDecl *ClassMethod = nullptr;
+  ObjCMethodDecl *InstanceMethod = nullptr;
+  TypedefNameDecl *TDNDecl = nullptr;
+  if (!checkObjCBridgeRelatedComponents(Loc, DestType, SrcType, RelatedClass,
+                                        ClassMethod, InstanceMethod, TDNDecl,
+                                        CfToNs, Diagnose))
+    return false;
+
+  if (CfToNs) {
+    // Implicit conversion from CF to ObjC object is needed.
+    if (ClassMethod) {
+      if (Diagnose) {
+        std::string ExpressionString = "[";
+        ExpressionString += RelatedClass->getNameAsString();
+        ExpressionString += " ";
+        ExpressionString += ClassMethod->getSelector().getAsString();
+        SourceLocation SrcExprEndLoc =
+            getLocForEndOfToken(SrcExpr->getEndLoc());
+        // Provide a fixit: [RelatedClass ClassMethod SrcExpr]
+        Diag(Loc, diag::err_objc_bridged_related_known_method)
+            << SrcType << DestType << ClassMethod->getSelector() << false
+            << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(),
+                                          ExpressionString)
+            << FixItHint::CreateInsertion(SrcExprEndLoc, "]");
+        Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
+        Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+
+        QualType receiverType = Context.getObjCInterfaceType(RelatedClass);
+        // Argument.
+        Expr *args[] = { SrcExpr };
+        ExprResult msg = BuildClassMessageImplicit(receiverType, false,
+                                      ClassMethod->getLocation(),
+                                      ClassMethod->getSelector(), ClassMethod,
+                                      MultiExprArg(args, 1));
+        SrcExpr = msg.get();
+      }
+      return true;
+    }
+  }
+  else {
+    // Implicit conversion from ObjC type to CF object is needed.
+    if (InstanceMethod) {
+      if (Diagnose) {
+        std::string ExpressionString;
+        SourceLocation SrcExprEndLoc =
+            getLocForEndOfToken(SrcExpr->getEndLoc());
+        if (InstanceMethod->isPropertyAccessor())
+          if (const ObjCPropertyDecl *PDecl =
+                  InstanceMethod->findPropertyDecl()) {
+            // fixit: ObjectExpr.propertyname when it is  aproperty accessor.
+            ExpressionString = ".";
+            ExpressionString += PDecl->getNameAsString();
+            Diag(Loc, diag::err_objc_bridged_related_known_method)
+                << SrcType << DestType << InstanceMethod->getSelector() << true
+                << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
+          }
+        if (ExpressionString.empty()) {
+          // Provide a fixit: [ObjectExpr InstanceMethod]
+          ExpressionString = " ";
+          ExpressionString += InstanceMethod->getSelector().getAsString();
+          ExpressionString += "]";
+
+          Diag(Loc, diag::err_objc_bridged_related_known_method)
+              << SrcType << DestType << InstanceMethod->getSelector() << true
+              << FixItHint::CreateInsertion(SrcExpr->getBeginLoc(), "[")
+              << FixItHint::CreateInsertion(SrcExprEndLoc, ExpressionString);
+        }
+        Diag(RelatedClass->getBeginLoc(), diag::note_declared_at);
+        Diag(TDNDecl->getBeginLoc(), diag::note_declared_at);
+
+        ExprResult msg =
+          BuildInstanceMessageImplicit(SrcExpr, SrcType,
+                                       InstanceMethod->getLocation(),
+                                       InstanceMethod->getSelector(),
+                                       InstanceMethod, None);
+        SrcExpr = msg.get();
+      }
+      return true;
+    }
+  }
+  return false;
+}
+
+Sema::ARCConversionResult
+Sema::CheckObjCConversion(SourceRange castRange, QualType castType,
+                          Expr *&castExpr, CheckedConversionKind CCK,
+                          bool Diagnose, bool DiagnoseCFAudited,
+                          BinaryOperatorKind Opc) {
+  QualType castExprType = castExpr->getType();
+
+  // For the purposes of the classification, we assume reference types
+  // will bind to temporaries.
+  QualType effCastType = castType;
+  if (const ReferenceType *ref = castType->getAs<ReferenceType>())
+    effCastType = ref->getPointeeType();
+
+  ARCConversionTypeClass exprACTC = classifyTypeForARCConversion(castExprType);
+  ARCConversionTypeClass castACTC = classifyTypeForARCConversion(effCastType);
+  if (exprACTC == castACTC) {
+    // Check for viability and report error if casting an rvalue to a
+    // life-time qualifier.
+    if (castACTC == ACTC_retainable &&
+        (CCK == CCK_CStyleCast || CCK == CCK_OtherCast) &&
+        castType != castExprType) {
+      const Type *DT = castType.getTypePtr();
+      QualType QDT = castType;
+      // We desugar some types but not others. We ignore those
+      // that cannot happen in a cast; i.e. auto, and those which
+      // should not be de-sugared; i.e typedef.
+      if (const ParenType *PT = dyn_cast<ParenType>(DT))
+        QDT = PT->desugar();
+      else if (const TypeOfType *TP = dyn_cast<TypeOfType>(DT))
+        QDT = TP->desugar();
+      else if (const AttributedType *AT = dyn_cast<AttributedType>(DT))
+        QDT = AT->desugar();
+      if (QDT != castType &&
+          QDT.getObjCLifetime() !=  Qualifiers::OCL_None) {
+        if (Diagnose) {
+          SourceLocation loc = (castRange.isValid() ? castRange.getBegin()
+                                                    : castExpr->getExprLoc());
+          Diag(loc, diag::err_arc_nolifetime_behavior);
+        }
+        return ACR_error;
+      }
+    }
+    return ACR_okay;
+  }
+
+  // The life-time qualifier cast check above is all we need for ObjCWeak.
+  // ObjCAutoRefCount has more restrictions on what is legal.
+  if (!getLangOpts().ObjCAutoRefCount)
+    return ACR_okay;
+
+  if (isAnyCLike(exprACTC) && isAnyCLike(castACTC)) return ACR_okay;
+
+  // Allow all of these types to be cast to integer types (but not
+  // vice-versa).
+  if (castACTC == ACTC_none && castType->isIntegralType(Context))
+    return ACR_okay;
+
+  // Allow casts between pointers to lifetime types (e.g., __strong id*)
+  // and pointers to void (e.g., cv void *). Casting from void* to lifetime*
+  // must be explicit.
+  // Allow conversions between pointers to lifetime types and coreFoundation
+  // pointers too, but only when the conversions are explicit.
+  if (exprACTC == ACTC_indirectRetainable &&
+      (castACTC == ACTC_voidPtr ||
+       (castACTC == ACTC_coreFoundation && isCast(CCK))))
+    return ACR_okay;
+  if (castACTC == ACTC_indirectRetainable &&
+      (exprACTC == ACTC_voidPtr || exprACTC == ACTC_coreFoundation) &&
+      isCast(CCK))
+    return ACR_okay;
+
+  switch (ARCCastChecker(Context, exprACTC, castACTC, false).Visit(castExpr)) {
+  // For invalid casts, fall through.
+  case ACC_invalid:
+    break;
+
+  // Do nothing for both bottom and +0.
+  case ACC_bottom:
+  case ACC_plusZero:
+    return ACR_okay;
+
+  // If the result is +1, consume it here.
+  case ACC_plusOne:
+    castExpr = ImplicitCastExpr::Create(Context, castExpr->getType(),
+                                        CK_ARCConsumeObject, castExpr, nullptr,
+                                        VK_PRValue, FPOptionsOverride());
+    Cleanup.setExprNeedsCleanups(true);
+    return ACR_okay;
+  }
+
+  // If this is a non-implicit cast from id or block type to a
+  // CoreFoundation type, delay complaining in case the cast is used
+  // in an acceptable context.
+  if (exprACTC == ACTC_retainable && isAnyRetainable(castACTC) && isCast(CCK))
+    return ACR_unbridged;
+
+  // Issue a diagnostic about a missing @-sign when implicit casting a cstring
+  // to 'NSString *', instead of falling through to report a "bridge cast"
+  // diagnostic.
+  if (castACTC == ACTC_retainable && exprACTC == ACTC_none &&
+      CheckConversionToObjCLiteral(castType, castExpr, Diagnose))
+    return ACR_error;
+
+  // Do not issue "bridge cast" diagnostic when implicit casting
+  // a retainable object to a CF type parameter belonging to an audited
+  // CF API function. Let caller issue a normal type mismatched diagnostic
+  // instead.
+  if ((!DiagnoseCFAudited || exprACTC != ACTC_retainable ||
+       castACTC != ACTC_coreFoundation) &&
+      !(exprACTC == ACTC_voidPtr && castACTC == ACTC_retainable &&
+        (Opc == BO_NE || Opc == BO_EQ))) {
+    if (Diagnose)
+      diagnoseObjCARCConversion(*this, castRange, castType, castACTC, castExpr,
+                                castExpr, exprACTC, CCK);
+    return ACR_error;
+  }
+  return ACR_okay;
+}
+
+/// Given that we saw an expression with the ARCUnbridgedCastTy
+/// placeholder type, complain bitterly.
+void Sema::diagnoseARCUnbridgedCast(Expr *e) {
+  // We expect the spurious ImplicitCastExpr to already have been stripped.
+  assert(!e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
+  CastExpr *realCast = cast<CastExpr>(e->IgnoreParens());
+
+  SourceRange castRange;
+  QualType castType;
+  CheckedConversionKind CCK;
+
+  if (CStyleCastExpr *cast = dyn_cast<CStyleCastExpr>(realCast)) {
+    castRange = SourceRange(cast->getLParenLoc(), cast->getRParenLoc());
+    castType = cast->getTypeAsWritten();
+    CCK = CCK_CStyleCast;
+  } else if (ExplicitCastExpr *cast = dyn_cast<ExplicitCastExpr>(realCast)) {
+    castRange = cast->getTypeInfoAsWritten()->getTypeLoc().getSourceRange();
+    castType = cast->getTypeAsWritten();
+    CCK = CCK_OtherCast;
+  } else {
+    llvm_unreachable("Unexpected ImplicitCastExpr");
+  }
+
+  ARCConversionTypeClass castACTC =
+    classifyTypeForARCConversion(castType.getNonReferenceType());
+
+  Expr *castExpr = realCast->getSubExpr();
+  assert(classifyTypeForARCConversion(castExpr->getType()) == ACTC_retainable);
+
+  diagnoseObjCARCConversion(*this, castRange, castType, castACTC,
+                            castExpr, realCast, ACTC_retainable, CCK);
+}
+
+/// stripARCUnbridgedCast - Given an expression of ARCUnbridgedCast
+/// type, remove the placeholder cast.
+Expr *Sema::stripARCUnbridgedCast(Expr *e) {
+  assert(e->hasPlaceholderType(BuiltinType::ARCUnbridgedCast));
+
+  if (ParenExpr *pe = dyn_cast<ParenExpr>(e)) {
+    Expr *sub = stripARCUnbridgedCast(pe->getSubExpr());
+    return new (Context) ParenExpr(pe->getLParen(), pe->getRParen(), sub);
+  } else if (UnaryOperator *uo = dyn_cast<UnaryOperator>(e)) {
+    assert(uo->getOpcode() == UO_Extension);
+    Expr *sub = stripARCUnbridgedCast(uo->getSubExpr());
+    return UnaryOperator::Create(Context, sub, UO_Extension, sub->getType(),
+                                 sub->getValueKind(), sub->getObjectKind(),
+                                 uo->getOperatorLoc(), false,
+                                 CurFPFeatureOverrides());
+  } else if (GenericSelectionExpr *gse = dyn_cast<GenericSelectionExpr>(e)) {
+    assert(!gse->isResultDependent());
+
+    unsigned n = gse->getNumAssocs();
+    SmallVector<Expr *, 4> subExprs;
+    SmallVector<TypeSourceInfo *, 4> subTypes;
+    subExprs.reserve(n);
+    subTypes.reserve(n);
+    for (const GenericSelectionExpr::Association assoc : gse->associations()) {
+      subTypes.push_back(assoc.getTypeSourceInfo());
+      Expr *sub = assoc.getAssociationExpr();
+      if (assoc.isSelected())
+        sub = stripARCUnbridgedCast(sub);
+      subExprs.push_back(sub);
+    }
+
+    return GenericSelectionExpr::Create(
+        Context, gse->getGenericLoc(), gse->getControllingExpr(), subTypes,
+        subExprs, gse->getDefaultLoc(), gse->getRParenLoc(),
+        gse->containsUnexpandedParameterPack(), gse->getResultIndex());
+  } else {
+    assert(isa<ImplicitCastExpr>(e) && "bad form of unbridged cast!");
+    return cast<ImplicitCastExpr>(e)->getSubExpr();
+  }
+}
+
+bool Sema::CheckObjCARCUnavailableWeakConversion(QualType castType,
+                                                 QualType exprType) {
+  QualType canCastType =
+    Context.getCanonicalType(castType).getUnqualifiedType();
+  QualType canExprType =
+    Context.getCanonicalType(exprType).getUnqualifiedType();
+  if (isa<ObjCObjectPointerType>(canCastType) &&
+      castType.getObjCLifetime() == Qualifiers::OCL_Weak &&
+      canExprType->isObjCObjectPointerType()) {
+    if (const ObjCObjectPointerType *ObjT =
+        canExprType->getAs<ObjCObjectPointerType>())
+      if (const ObjCInterfaceDecl *ObjI = ObjT->getInterfaceDecl())
+        return !ObjI->isArcWeakrefUnavailable();
+  }
+  return true;
+}
+
+/// Look for an ObjCReclaimReturnedObject cast and destroy it.
+static Expr *maybeUndoReclaimObject(Expr *e) {
+  Expr *curExpr = e, *prevExpr = nullptr;
+
+  // Walk down the expression until we hit an implicit cast of kind
+  // ARCReclaimReturnedObject or an Expr that is neither a Paren nor a Cast.
+  while (true) {
+    if (auto *pe = dyn_cast<ParenExpr>(curExpr)) {
+      prevExpr = curExpr;
+      curExpr = pe->getSubExpr();
+      continue;
+    }
+
+    if (auto *ce = dyn_cast<CastExpr>(curExpr)) {
+      if (auto *ice = dyn_cast<ImplicitCastExpr>(ce))
+        if (ice->getCastKind() == CK_ARCReclaimReturnedObject) {
+          if (!prevExpr)
+            return ice->getSubExpr();
+          if (auto *pe = dyn_cast<ParenExpr>(prevExpr))
+            pe->setSubExpr(ice->getSubExpr());
+          else
+            cast<CastExpr>(prevExpr)->setSubExpr(ice->getSubExpr());
+          return e;
+        }
+
+      prevExpr = curExpr;
+      curExpr = ce->getSubExpr();
+      continue;
+    }
+
+    // Break out of the loop if curExpr is neither a Paren nor a Cast.
+    break;
+  }
+
+  return e;
+}
+
+ExprResult Sema::BuildObjCBridgedCast(SourceLocation LParenLoc,
+                                      ObjCBridgeCastKind Kind,
+                                      SourceLocation BridgeKeywordLoc,
+                                      TypeSourceInfo *TSInfo,
+                                      Expr *SubExpr) {
+  ExprResult SubResult = UsualUnaryConversions(SubExpr);
+  if (SubResult.isInvalid()) return ExprError();
+  SubExpr = SubResult.get();
+
+  QualType T = TSInfo->getType();
+  QualType FromType = SubExpr->getType();
+
+  CastKind CK;
+
+  bool MustConsume = false;
+  if (T->isDependentType() || SubExpr->isTypeDependent()) {
+    // Okay: we'll build a dependent expression type.
+    CK = CK_Dependent;
+  } else if (T->isObjCARCBridgableType() && FromType->isCARCBridgableType()) {
+    // Casting CF -> id
+    CK = (T->isBlockPointerType() ? CK_AnyPointerToBlockPointerCast
+                                  : CK_CPointerToObjCPointerCast);
+    switch (Kind) {
+    case OBC_Bridge:
+      break;
+
+    case OBC_BridgeRetained: {
+      bool br = isKnownName("CFBridgingRelease");
+      Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
+        << 2
+        << FromType
+        << (T->isBlockPointerType()? 1 : 0)
+        << T
+        << SubExpr->getSourceRange()
+        << Kind;
+      Diag(BridgeKeywordLoc, diag::note_arc_bridge)
+        << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge");
+      Diag(BridgeKeywordLoc, diag::note_arc_bridge_transfer)
+        << FromType << br
+        << FixItHint::CreateReplacement(BridgeKeywordLoc,
+                                        br ? "CFBridgingRelease "
+                                           : "__bridge_transfer ");
+
+      Kind = OBC_Bridge;
+      break;
+    }
+
+    case OBC_BridgeTransfer:
+      // We must consume the Objective-C object produced by the cast.
+      MustConsume = true;
+      break;
+    }
+  } else if (T->isCARCBridgableType() && FromType->isObjCARCBridgableType()) {
+    // Okay: id -> CF
+    CK = CK_BitCast;
+    switch (Kind) {
+    case OBC_Bridge:
+      // Reclaiming a value that's going to be __bridge-casted to CF
+      // is very dangerous, so we don't do it.
+      SubExpr = maybeUndoReclaimObject(SubExpr);
+      break;
+
+    case OBC_BridgeRetained:
+      // Produce the object before casting it.
+      SubExpr = ImplicitCastExpr::Create(Context, FromType, CK_ARCProduceObject,
+                                         SubExpr, nullptr, VK_PRValue,
+                                         FPOptionsOverride());
+      break;
+
+    case OBC_BridgeTransfer: {
+      bool br = isKnownName("CFBridgingRetain");
+      Diag(BridgeKeywordLoc, diag::err_arc_bridge_cast_wrong_kind)
+        << (FromType->isBlockPointerType()? 1 : 0)
+        << FromType
+        << 2
+        << T
+        << SubExpr->getSourceRange()
+        << Kind;
+
+      Diag(BridgeKeywordLoc, diag::note_arc_bridge)
+        << FixItHint::CreateReplacement(BridgeKeywordLoc, "__bridge ");
+      Diag(BridgeKeywordLoc, diag::note_arc_bridge_retained)
+        << T << br
+        << FixItHint::CreateReplacement(BridgeKeywordLoc,
+                          br ? "CFBridgingRetain " : "__bridge_retained");
+
+      Kind = OBC_Bridge;
+      break;
+    }
+    }
+  } else {
+    Diag(LParenLoc, diag::err_arc_bridge_cast_incompatible)
+      << FromType << T << Kind
+      << SubExpr->getSourceRange()
+      << TSInfo->getTypeLoc().getSourceRange();
+    return ExprError();
+  }
+
+  Expr *Result = new (Context) ObjCBridgedCastExpr(LParenLoc, Kind, CK,
+                                                   BridgeKeywordLoc,
+                                                   TSInfo, SubExpr);
+
+  if (MustConsume) {
+    Cleanup.setExprNeedsCleanups(true);
+    Result = ImplicitCastExpr::Create(Context, T, CK_ARCConsumeObject, Result,
+                                      nullptr, VK_PRValue, FPOptionsOverride());
+  }
+
+  return Result;
+}
+
+ExprResult Sema::ActOnObjCBridgedCast(Scope *S,
+                                      SourceLocation LParenLoc,
+                                      ObjCBridgeCastKind Kind,
+                                      SourceLocation BridgeKeywordLoc,
+                                      ParsedType Type,
+                                      SourceLocation RParenLoc,
+                                      Expr *SubExpr) {
+  TypeSourceInfo *TSInfo = nullptr;
+  QualType T = GetTypeFromParser(Type, &TSInfo);
+  if (Kind == OBC_Bridge)
+    CheckTollFreeBridgeCast(T, SubExpr);
+  if (!TSInfo)
+    TSInfo = Context.getTrivialTypeSourceInfo(T, LParenLoc);
+  return BuildObjCBridgedCast(LParenLoc, Kind, BridgeKeywordLoc, TSInfo,
+                              SubExpr);
+}